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Subject Payment

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The primary ethical issue is the concern that payment will inappropriately influence subjects’ decision about participating in the research and about staying in the study once enrolled. This is called undue influence.

Researchers should think about payment by category in order to assess the potential for undue influence. Reimbursement and compensation are less likely to unduly influence subjects than incentives are. Expand the list below for links to key guidance on minimizing the possibility of undue influence.

Purpose and Applicability

This is guidance and a framework for designing and evaluating reimbursement, compensation, and incentives offered to subjects for participating in research, for use by the Human Subjects Division, UW Institutional Review Boards (IRBs), and researchers. Unless specifically stated, the word “payment” is used generically to refer to all types of reimbursement, compensation, and incentives, both financial and non-financial. This guidance does not address the issue of how subject decisions might be influenced by the financial value of the research procedures themselves – it is a related but different issue that should be considered separately by researchers and IRBs.


Federal human subjects regulations are silent on payment for research subjects, noting only that: 1) researchers shall provide prospective subjects with a consent process that allows sufficient opportunity to discuss and consider whether or not to participate and that minimizes the possibility of coercion or undue influence; and 2) when some or all of the subjects are likely to be vulnerable to undue influence (e.g., children, prisoners, decisionally-impaired individuals), the IRB should consider additional safeguards to protect subject rights and welfare. While the regulations are silent, federal guidance notes that paying research subjects is a common and generally acceptable practice and that payment for participation in research should be just and fair.

This guidance and framework is based on HSD’s evaluation of federal regulatory agency guidance as well as several peer-reviewed publications by prominent research ethicists that are widely accepted as well-reasoned and useful analyses of subject payment (see references below). A significant amount of prose is paraphrased from those publications. The framework presented here was developed from SACHRP recommendations and Gelinas et al (2018). HSD has broadened this framework to include non-financial incentives such as subjects’ access to specific items or services through research and return of results. This generalization is based on HSD’s interpretation of recent peer-reviewed ethical analyses of specific payment issues.

The examples in this guidance are provided to demonstrate concepts. They are not recommendations or requirements for payment rates or structures.

What is Undue Influence?

The primary ethical issue

The primary ethical issue about offering payment to subjects is the concern that the payment will inappropriately influence their decision about participating in the research and about staying in the study once enrolled. This is called undue influence. It is important to understand how this is different from coercion or mere influence.

Distinguishing coercion from undue influence

According to federal guidance, coercion occurs when an overt or implicit threat of harm is intentionally presented by one person to another in order to obtain compliance while undue influence may occur through an excessive offer of something valuable or desirable that influences decision-making in inappropriate ways. Based on these definitions, payments for subjects cannot be coercive because it is an offer of something desirable rather than a threat. However, payments for subjects do have the potential to be unduly influential.

Distinguishing mere influence from undue influence

While merely influential payments color subjects’ judgment while they consider reasonable choices, unduly influential payments cloud subjects’ judgment while they consider unreasonable choices. Federal guidance notes there are no fixed standards for distinguishing what is merely influential from what is unduly influential. This means it is up to the IRB and researchers to use judgment in making this distinction. In general, payments for participation raise concerns about undue influence when they appear likely to:

  • Inhibit potential participants’ adequate consideration of, and reflection about, important study features such as risks, burdens, and discomforts; or
  • Impair their understanding of the research and their participation in it.

Incentive Compared with Reimbursement and Compensation


Reimbursement for out-of-pocket expenses (e.g., travel, parking, meals, lodging) is generally acknowledged to be fair and appropriate so that subjects do not bear financial burdens for volunteering to participate in research. Once reimbursed, subjects are returned to their pre-enrollment financial baseline, meaning there is no net benefit from the payment. Without a net benefit, it is not possible for the payment to be unduly influential, so long as the reimbursement is appropriately estimated. This analysis is consistent with federal guidance.

Example: Researchers provide subjects with a $5 reimbursement to cover parking expenses for each in-clinic study visit. The researchers determine that $5 is appropriate because that is the cost of parking in the garage that adjoins the clinic and is also roughly the cost of a round-trip city bus ride.
Example: To meet recruitment goals, researchers expand eligibility to individuals who live outside of the state in which the research is being conducted. The researchers reimburse out-of-state subjects for the costs of airfare and lodging and provide subjects with a daily stipend of $75 for meals. The stipend is calculated by looking at menu prices for restaurants in the neighborhood where the clinic and hotel are located.


Compensation may be offered to subjects to offset the time and burdens of research participation. For many subjects, research participation may mean forgoing other sources of income. Providing compensation helps to make enrolling in research as attractive, rather than more attractive, than other ways of spending time. Compensation generally does not unduly influence subjects to participate in research, so long as it is appropriately estimated.

Example: A study is being conducted in a city where the local average wage is $15/hour. Subjects will be asked to make three clinic visits, lasting 2-3 hours each. Procedures include blood draws, one MRI, one optional lymph node biopsy, and several questionnaires and surveys. Researchers propose paying subjects $45 per visit ($15 x 3hrs) with an additional $150 to those who opt to undergo the biopsy. Subjects will receive the $150 for the biopsy procedure even if a lymph node is not successfully biopsied.
Example: Researchers are recruiting two subject groups. Group A will take a series of surveys which will take approximately 1.5 hours to complete. Group B will take the same series of surveys and will complete an additional task that will take another 30 minutes. Researchers propose paying Group A $23 (1.5 hours x $15/hr average local wage) and Group B $30 (2 hours x $15/hr).
Example. Researchers are recruiting adult subjects to complete short crowd-sourced evaluations on Amazon’s Mechanical Turk. Subjects will be paid for each task they complete at a rate of $15/hour, which the researchers think is appropriate for the difficulty of the task and average amount of time predicted to complete the task.
Example. Researchers are recruiting for a longitudinal study in which subjects complete a quarterly survey for up to 5 years. Research propose paying subjects $30 for every survey they complete.


Unlike reimbursement or compensation which seek, respectively, to restore subjects to a pre-research financial baseline or to acknowledge the time and burdens of participating in research, incentives are intended to improve recruitment and retention by influencing subjects to enroll, remain enrolled in the research, and complete specific or all procedures and milestones. Incentives may be financial (for example, a cash payment or a gift card) or they may be non-financial (for example, class credit or the return of a subject’s genetic testing results). Undue influence generally arises from incentives as opposed to reimbursement or compensation.

Minimizing the Possibility of Undue Influence: A Balancing Issue

Minimizing versus eliminating undue influence

Researchers and the IRBs are tasked with minimizing the possibility of undue influence, not eliminating it. This is accomplished by considering the specifics of each study, the subject population, the payment plan, the IRB criteria for approval, and the consent process.

Researcher Responsibilities

  • Know the difference between mere influence and undue influence.
  • Understand that undue influence is more likely to arise from incentives than from reimbursement or compensation. This means that minimizing undue influence is generally most necessary when payment consists of incentives.
  • Balance the consideration of undue influence with the impact of incentives on other aspects of the study (e.g., realizing the study benefits by successfully recruiting enough participants; impact on the diversity of the study population).

IRB Responsibilities

  • Know the difference between mere influence and undue influence.
  • Understand that undue influence is more likely to arise from incentives than from reimbursement or compensation. This means that minimizing undue influence is generally most necessary when payment consists of incentives.
  • Balance the consideration of undue influence with the impact of incentives on other aspects of the study (e.g., realizing the study benefits by successfully recruiting enough participants; impact on the diversity of the study population).

Population-specific issues

Motivations for participation are varied among individuals and populations, with studies consistently reporting the significant importance of altruistic motivations and general curiosity. However, additional safeguards with respect to undue influence of payments may be appropriate for specific populations. Payments that would be acceptable for a general subject population may be unduly influential for specific subject groups. Populations that may require special consideration include (but are not limited to):


The possibility for undue influence must be considered separately for the child participating in research and the parent providing permission.

  • Children. The payment plan should consider the age of the child and their ability to assess the value of the payment against the research contribution they are making.
    In general, a toy may be a more appropriate incentive or compensation for younger subjects while a gift card or cash may be more appropriate for an adolescent. Incentives and compensation for the child should generally be given directly to the child, rather than the parent.
  • Parents. It may be acceptable to reimburse or compensate parents for the costs and burden experienced by facilitating their child’s participation in research, if the amounts are not likely to cloud the parent’s judgement about what is best for the child. Incentive payments to parents who are not also study subjects are generally not appropriate.


There is wide variation in whether federal, state, and local institutions consider it appropriate to provide research compensation or incentives to incarcerated individuals.

The UW IRB allows compensation and incentives to incarcerated subjects, if appropriate and allowed by the institution(s). However, compensation and incentives may be more likely to be unduly influential because of the limited opportunities prisoners have to earn money and to obtain specific items or services as well as the inherent limitations on their autonomy resulting from their incarceration.

Although there are no quantitative studies measuring actual undue influence in incarcerated subjects, several qualitative studies have been conducted asking prisoners about their experience with research and their perceptions about undue influence related to payment. These studies found that prisoners think they should be compensated for their contribution, that payment is a motivator for enrolling but is generally not the only or the primary motivator, and that the prisoners would likely still enroll in a study even without compensation. Of concern, one study found that the potential for undue influence was significantly higher among prisoners with lower educational attainment and those who had spent a longer time in prison. So, just like with all other populations, the likelihood of payment unduly influencing incarcerated subjects to enroll in research will vary depending on the subject and the study specifics.

Other groups

Vulnerable populations are groups of subjects who may be at higher risk of undue influence or who may be unable to easily understand the consent information. This may include, but is not limited to: individuals who are decisionally-impaired; individuals of lower socio-economic status; illiterate individuals; individuals with low educational attainment; non-English speakers or speakers of English as a second language; undocumented migrants; and subjects with addiction issues. The particulars of how to minimize the likelihood of undue influence for a vulnerable population will depend on the specifics of the study and subject population.

Researcher Responsibilities

  • When participants will be recruited from specific locations (e.g., another country) or institutions (e.g., prisons; schools), find out whether there are specific limits or requirements for paying subjects.
  • Researchers are expected to be knowledgeable about their study population(s). Consider whether the study population may be more vulnerable to the possibility of undue influence. If yes, consider additional protections such as:
    • Follow the payment guidelines described above for prisoners and children
    • Design a payment plan with specific details that are appropriate for the population
    • Design a robust process for consent, assent, and parental permission
    • Develop recruiting materials that take the specific population issues into account
  • Consider consulting with advocates or members of the proposed subject population for feedback about payment and the consent process. For example, such consultation might help researchers to decide whether it is overly paternalistic or is it an appropriate harm reduction strategy to provide an appreciation gift or grocery store gift cards rather than cash incentives for subjects who are dealing with addiction issues.
  • It is likely that the IRB review will benefit from researchers providing a rationale in the IRB application for the type, nature, and amount of subject payments and why they are appropriate for the study population.

IRB Responsibilities

  • Assess whether any study populations may be especially vulnerable to undue influence.
  • Assess the researcher’s rationale (if provided) for the specific payment plan in the context of the specific study population(s). If a rationale is not provided but the IRB has questions about the plan, ask the researcher for the rationale.
  • For studies with prisoners: The prisoner advocate should evaluate the payment plan and share any concerns with the IRB. Careful consideration of the additional protections described for prisoners in Subpart C of the Common Rule can help minimize the possibility of undue influence (or can provide context that alleviates concern about undue influence).
  • For studies with children or other possibly vulnerable populations: Consider consulting someone who has expertise with the study population. Careful consideration of the additional protections described for children in Subpart D of the Common Rule can help minimize the possibility of undue influence (or can provide context that alleviates concern about undue influence).

The payment plan

Elements of a payment plan

A well-designed payment plan should specify these elements:

  • Reimbursement, compensation and/or incentives. Which of these categories of payment will be offered? Reimbursement and compensation are nationally recognized to be an issue of fairness to subjects and an ethical best practice that is especially encouraged for funded clinical research. For some studies, a single payment may be intended to address all three categories of payment. For other studies, there may be incentive payments that are separate from reimbursement or compensation.
  • Type (method) of payment. How will the payment be provided? Examples: check, cash, gift card, toy, drawing for a prize, class credit. Note that the options for reimbursement and compensation are somewhat limited (e.g., cash, check, gift card) whereas there are many possible options for incentives.
  • Amount. How much will be provided? The amount should not be unduly influential for the circumstances and study population. Factors to consider:
    • Reimbursement. Consider the amount of out-of-pocket expenses for participants, including (for clinical research) any health insurance co-pays or deductibles. Which will be reimbursed? Will reimbursement be for actual expenses, or for an average/typical amount? Will participation expenses be balanced by other payments associated with the research (e.g., compensation; a single combined payment intended to provide reimbursement plus some incentive) or by study-delivered services or return of individual study results?
    • Compensation. Consider the time and effort (burden) associated with participation. What will be the basis for determining the amount of compensation? Examples: an hourly rate based on the average hourly wage in the research location; a set amount for the time and effort associated with specific procedures or study visits.
    • Relationship with risk. Federal guidance states that it is acceptable to consider the study risks when deciding on the incentive amount. Empirical studies (e.g., see References) have consistently shown that large incentives are generally considered an indicator of study risks by participants. If risk level is part of the rationale for a large incentive, then it may help minimize the possibility of undue influence to state in the consent process that the size of the incentive was chosen to be appropriate for the risks of the study.
    • Impact on enrollment goals. Payment may affect whether enrollment goals are met (and therefore affect the overall benefit of conducting the study).
    • Impact on population diversity. Payment amounts may influence the diversity of the enrolled participants and therefore the generalizability (societal benefits) of the research. For example, if unreimbursed expenses are significant, individuals with lower income and/or inflexible working arrangements may not be able to afford to participate. For some research, this could result in a significantly unrepresentative study population.
    • Potential exploitation may be an ethical concern if subjects are not offered adequate compensation or other benefits compared to the value of their contribution. When the costs and burden of volunteering for research are high, higher payments may be warranted.
  • Pro-rating. Prorating means dividing up the total payment into two or more payments across time. This reduces the possibility that subjects will stay in a study just to receive the payment when they would otherwise choose to withdraw from it. If appropriate, the payment schedule should reflect that subjects will receive reimbursement and compensation payments as the study progresses and for all procedures completed, regardless of whether a subject completes the study, withdraws, or is withdrawn. For studies of short duration (e.g., a few weeks) it may be acceptable to pay only at the end of the subject’s participation, but for studies of longer duration (e.g., several months), there should be multiple payment points (e.g., monthly or after some set number of sessions). Pro-rating is an important way to reduce the possibility of undue influence that the UW IRB strongly encourages and may require.

Researcher Responsibilities

  • The IRB application should include a detailed description of the specific elements of the payment plan, including whether payments are intended to be reimbursement, compensation, and/or incentives and the type of payment that will be offered
  • Be prepared to provide the IRB with a justification for the amount that will be provided.
  • If there are population-specific issues, describe the rationale for how the payment plan has been tailored to the population.
  • Describe the details of any pro-rating.

IRB Responsibilities

  • Assess the description of the payment plan to ensure that all relevant details have been provided.
  • Assess the proposed payment for the likelihood that it will be unduly influential given the study location, procedures, and study population. It is especially important to consider the category of payment (i.e., reimbursement, compensation, incentive), the amount of payment, how it will be provided, and whether there is pro-rating. If a single payment is being offered, consider how much of it is reimbursement versus compensation versus incentive, keeping in mind that reimbursement and compensation generally do not exert undue influence. Consider whether additional information is required from the researchers in order to make this assessment, such as requesting a justification for the amount of payment proposed.
  • Consider the possible positive impacts the proposed payment may have on the research such as assisting in diversity of recruitment or encouraging completion of study milestones.
  • Understand that, in the absence of specific regulatory requirements, many ethicists believe that IRBs have sometimes imposed unnecessarily conservative limitations on the size of incentives.
  • Make use of recent peer-reviewed ethical analyses and empirical research about the impact of incentives on participants. These consistently indicate that limiting incentives may not be as protective as previously thought and may have negative consequences in some circumstances. See the References at the end of this guidance.

The consent process

The role of informed consent

Designing a consent form and process that supports and promotes autonomous and informed decision-making can help minimize the likelihood that prospective subjects will ignore or misunderstand study risks or other key information because of their interest in receiving payment. This includes an ongoing consent process that ensures subjects comprehend risks throughout the study and are updated about any changes to risks and benefits. An adequate consent process allows participants to decline participation in research that would be subjectively harmful according to their own judgement of their interests, values, and obligations.

Examples of how a well-designed consent process can minimize possible undue influence:

  • A substantive consent discussion tailored to the specific needs (e.g., education level) of the subject population. This is especially important for vulnerable populations.
  • Allowing sufficient time for subjects to consider participation and/or incorporating a waiting period between consent and enrollment.
  • Facilitating the subjects’ explicit consideration of their current (e.g., enrollment incentive) interests versus future interests (such as possible adverse events). This provides further support to individuals who feel they have “no choice” but to participate.
  • Providing details about the nature, amount, and timing of incentives, reimbursement, and compensation.

Payment information to provide as part of the consent process

Per nationally recognized best practice and UW IRB policy, the consent process (or consent form, if there is one) must provide the following payment information:

  • The total amount and method of reimbursement, compensation, incentives and/or combined payment; if appropriate, reimbursement and/or compensation may be described separately from incentives
  • If appropriate, a description of any pro-rating and when payment will occur for the procedures that have been completed if subjects withdraw or are withdrawn
  • Approximately how long it will take to receive payments. One of the most frequent subject complaints received by HSD is about the timing of payments; subjects typically expect that they will be paid as soon as they finish the study or promptly thereafter, but that rarely occurs.
  • If it is possible or likely that a subject participating in U.S. research will earn $600 or more in payments (not including reimbursements) for all UW studies in which they participate during the calendar year, those subjects must be informed that it is considered Miscellaneous Income and will be reported to the Internal Revenue Service for federal income tax purposes. See the FAQs for more information about federal income tax and subject payments.
  • Consider the study population when deciding whether participants should be informed that Social Security Numbers (SSNs) need to be collected for compensation and incentive payments (but not reimbursement). This might be of concern for populations such as gig workers, undocumented individuals, or foreign nationals. Note that HSD and the UW IRB can appropriately advise researchers about including this information in the consent process but cannot offer advice about when collection of SSNs is, or is not, required. UW Financial Management is responsible for compliance and advice about this requirement: https://finance.uw.edu/ps/how-pay/research-subjects.
  • If the size of any incentives is related to the study risks, consider whether subjects should be informed of the relationship by including a statement such as “This amount of money was selected as being appropriate for the level of risk to study participants”. Some controlled experimental research showed that such statements make participants more vigilant about seeking and viewing study risk information.
  • If applicable, a statement about anything for which subjects will not be compensated. For example, if biospecimens collected for research may result in commercial profit, subjects should be informed if they will not share in those potential profits.

Researcher Responsibilities

  • Design a robust consent process and consent form that support autonomous and informed decision-making at enrollment (if appropriate, throughout the study) and that is tailored to the target population being recruited.
  • Assess the payment method to determine how operational details (e.g., obtaining and providing a check or gift card) will affect the timing of the payment. Include the timing information in the consent process.
  • Provide all appropriate payment information as part of the consent process. Decide whether participants should be informed in the consent process about the collection of Social Security numbers.
  • Decide whether to inform participants about the relationship (if any) between the incentive amount and the study risk level.

IRB Responsibilities

  • Ensure that the consent process and form meet all applicable regulatory requirements, especially: Key Information section (if applicable), adequate opportunity for questions and decision-making, and any comprehension issues (e.g., reading level compared with the likely literacy and educational background of the participants), and appropriate description of risks.
  • Ensure that the consent process and form include all payment-related information of value to the specific study population.
  • It is not the IRB’s responsibility to require the collection of Social Security numbers (SSNs) nor to offer advice about when collection of SSNs is, or is not, required. This advice is the responsibility of UW Financial Management.

Recruiting process and materials

Advertising of IRB-approved payment is acceptable

Subjects must be made aware of the information so that it can facilitate enrollment, as it is intended to do. Payment information in recruiting materials should be truthful, clear, and not emphasized at the expense of other important information.

“At the expense of” means that the payment information is presented in the absence of other important information (e.g., research purpose; time commitment; brief description of procedures) or in a way that is likely to cause individuals to neglect or overlook the other information provided. In many cases, it is acceptable for payment information to be the featured or most prominent information so long as other important information is not missing or provided in hard-to-perceive ways.

Which study information (and how much) is included in recruiting materials is a function of the specific recruiting method and its information capacity (e.g., a small flyer posted on a bulletin board; a “cold contact” letter; a study website; Craig’s List posting)

Researcher Responsibilities

  • Design recruiting materials that provide the information that the study population will find most relevant and interesting. At a minimum this generally includes mention of the research purpose, time and effort involved, and whether there is any payment.

IRB Responsibilities

  • Assess the description of payment in recruiting materials to ensure that it contains the most relevant information for the study population (within the context of any space constraints).
  • Ensure that recruiting materials also provide the most relevant information (within any space constraints) for the study population, which may include: research purpose, location, time commitment, and summary of procedures.

IRB review

One of the most effective tools for minimizing the possibility of undue influence is rigorous IRB review based on a balanced consideration of the criteria for approval.

When IRBs focus on all the applicable criteria for approval and they approve consent processes and forms that protect and promote autonomous decision-making, it means the IRB has determined that participation in the study is likely to be a reasonable choice for the target population and that subjects are unlikely to be unduly influenced to participate in research.

This doesn’t mean that the study has no risks, but it does mean that agreeing to enroll in the study is not an unreasonable choice for the general study population, regardless of any payments.

Criteria for IRB approval

The IRB considers incentives, reimbursement, and compensation in the context of several IRB criteria for approval (and the Belmont ethical principles underlying those criteria):

  • Undue influence. Incentives should not be so large as to create undue influence on the decision to enroll and to remain enrolled (see What is Undue Influence, above). This is a difficult concern to address. For example, there is some evidence that rather than blinding subjects to risks or impairing comprehension, incentives (especially large ones) may increase levels of caution and perceptions of risk.
  • Vulnerable populations. An incentive that is not unduly influential for a general population may have a larger impact on specific populations (see Population Specific Issues).
  • Equitable selection of subjects. If the IRB limits payments in order to protect prospective subjects of lower socioeconomic status (SES) from undue influence, these individuals may still be encouraged by the payment to enroll but would receive a lower payment for their contribution. This strategy could also result in fewer subjects of a higher SES. An imbalanced representation of SES in the subject population could be contrary to the Belmont Report ethical principle of Justice with its emphasis on equal distribution of research risks, burdens, and benefits across populations.
  • Research benefits are likely to justify the risks.
    The benefit of most research is the knowledge or societal good that is likely to be gained. Limiting incentives for participation may be a hinderance to recruitment. If a study does not meet its recruitment goals and is therefore underpowered or terminated, it is unlikely that the research question can be answered. If the research question cannot be answered, then the IRB’s assessment that risks were reasonable in relation to anticipated benefits may no longer be appropriately balanced and subjects may have been exposed to risks for limited or no societal benefit. For example, low response rates are a known and common problem for electronic surveys. Low response rates can introduce bias, compromise the validity of the study, and increase the cost of conducting the study.There is some evidence that larger incentives may also result in a more diverse pool of research participants, which in turn may result in more representative and generalizable results as well as a more equal distribution of the potential benefits (individual and societal) of the research.
  • Identifying the procedures as research rather than other activities (such as clinical care or classroom instruction). Some recent evidence suggests that incentives may draw attention to the distinctions between research and clinical care. For example, if there is an additional, research blood draw associated with a clinical visit, compensating for the research blood draw may help draw attention to the fact that the blood draw is a research procedure instead of a clinical procedure.
Researcher Responsibilities
Provide an IRB application that includes all requested materials and that contains detailed and complete answers to all questions. Be prepared to provide rationales for the payment plan, if that information is requested by the IRB.

IRB Responsibilities

  • Carefully assess the proposed research against the regulatory criteria for approval, independently of any proposed payment.
  • Then consider the specific study population(s) and whether they are likely to be vulnerable to undue influence because of the proposed payment plan. If yes, identify the specific aspect(s) of the incentive that may result in undue influence (e.g., overall amount, lack of pro-rating; outsized completion bonus/incentive). What are acceptable approaches for reducing that possibility? Examples include: reducing the total incentive; spreading out the distribution of the incentive over a longer period of time; pro-rating more of the incentive; improving the consent process and information.
  • Consider the consent process and recruiting materials as described above.

Types of Payment: Minimizing Undue Influence and Other Considerations

What type of payment to offer

Consider these factors in addition to the possibility of undue influence.

The nature of the study population: What would be motivating for them?The possible cost and effort required for the subjects to make use of the payment.

Examples: A check cashing fee generally must be paid by subjects who don’t have bank accounts; subjects who don’t have ready access to a computer (or the technological knowledge) may not be able to make use of an online gift card; subjects may have difficulty traveling to the specific location where they can use a gift card if it is for a specific store or restaurant.

Age appropriateness

Cultural appropriateness

Privacy and confidentiality issues. There are many ways in which privacy or confidentiality concerns could arise with respect to payment. The relevance of these to the specific study circumstances should be considered. Some examples:

  • Subjects may be placed at risk if others observe them receiving cash or a check.
  • Incentives that are mailed to the subjects’ homes may go astray or be intercepted.
  • Checks, and payments requiring an online account, may create risks for undocumented individuals in this country.

Many payment methods require the involvement of finance and other administrative staff that are not part of the study team (e.g., department administrator, Shared Environment specialist, Tax Office). This is not considered a significant privacy and confidentiality risk, as the roles and responsibilities of these positions require discretion, confidentiality, and appropriate security measures and the information accessed is limited to that necessary to facilitate payment.

For researchers processing payments via Workday, you can minimize the association of private identifiable study data to the participant by ensuring use of a non-descript worktag name. Avoid using worktag names that include a study acronym that is searchable on the web or has the condition under study (e.g., GR12346 HIV Study). If a particular study population may have concerns that their financial information is accessible to others outside the study team, you can provide additional disclosure information as part of the consent process.

The logistics associated with each type of payment, including department and researcher responsibilities. For example, giving checks to subjects requires the establishment, management, and auditing of a checking account as well as independent financial controls. Department financial administrators should be able to answer questions about whether a specific method is possible or preferred.

The research budget

Legal and tax issues. There may be legal and tax issues associated with specific types/amounts of payments and specific study populations. The Human Subjects Division and the IRB cannot provide advice on these issues. Consult UW Financial Management through email or their Pay Research Subjects website. Examples of some considerations:

  • Payments made to foreign nationals in the U.S. must be made through a specific mechanism. In addition, those payments are automatically subject to 30% income tax withholding. In other words, paying subjects $100 means that foreign national subjects would actually receive a check for $70.
  • Payments to an individual must be reported by the UW to the U.S. Internal Revenue Service as Miscellaneous Income if the payments total $600 or more annually. This means that subject Social Security Numbers must be collected.
  • Questions about payment methods, income tax reporting, and collection of Social Security Numbers should be directed to UW Procurement Customer Service at pcshelp@uw.edu or 206.543.4500.

Cash and cash equivalents

There are many ways to offer cash or cash-equivalent incentives. Examples include but are not limited to: check; gift card to a store or restaurant; meal voucher; cash. Methods that have been vetted and are supported by the UW are described on the UW Finance website. It is important to establish appropriate financial controls for oversight and the prevention/detection of fraud and theft if a UW budget (e.g., a grant, or department funds) is being used to pay subjects.

Enrollment and completion incentives

Incentives may be provided to encourage general enrollment, target the enrollment of particular groups, or encourage completion of certain study milestones or the entire study. Federal guidance notes that these types of incentives are permissible when the IRB determines they are not likely to be unduly influential. Federal guidance and ethical analyses encourage the use of enrollment and completion incentives in clinical research only if the study also plans to reimburse and/or compensate subjects.

Example: Researchers anticipate recruitment and completion challenges for the clinical trial they have designed. They propose a $200 enrollment bonus payment and an additional $100 bonus payment for subjects who complete all study visits as scheduled. They also have a plan to reimburse and compensate subjects.
Example: Researchers are recruiting physicians and patients for a longitudinal survey study that provides a compensation rate of $5 per completed survey. Two months into the year-long study, physicians are under-enrolled and are not completing their weekly surveys at the same rate as the patient group. The researchers propose a $25 enrollment incentive for physicians and an additional $20 incentive for patient and physician subjects who complete all their weekly surveys.
Example: Three months into enrollment, researchers identify that several key demographic groups are under-enrolled. They propose a $50 enrollment incentive and some additional modifications to their recruitment plan to target those groups.

Goods, services, information, resources

These may be offered as incentives to enroll or complete a study. This is distinct and different from providing these items as an integral part of the study procedures. This guidance does not address the issue of how subject decisions might be influenced by the financial value of the research procedures themselves – it is a related but different issue that should be considered separately the researchers and IRBs.


  • Post-study drug availability. Subjects who complete a clinical trial with an experimental drug may be allowed to continue taking the drug through a drug company program.
  • Study devices and apps. Subjects may be allowed to retain devices, equipment or software applications that were used for study procedures.
  • Information, resources and referrals. These may be offered to subjects when they complete the study. Example: Individual results of specific tests.


Researchers may wish to provide incentives by holding a drawing in which each subject is entered and has an opportunity to win one of a limited number of incentives. The incentives might be cash, gift cards, goods, services, or resources. Studies have shown that drawings are especially effective for increasing the response rates for electronic surveys.

Minimizing the possibility of undue influence

Subjects should be informed of the value of the item, the approximate chance of winning (in the context of the expected enrollment), and the timing of the drawing. There should be a reasonable balance between the cash value of the prize and the number of prizes offered. The IRB may ask for the researcher’s justification if one item of significant value (e.g., an electronic tablet, a new smart phone) is being offered instead of several items of smaller value.

The Belmont principle of justice

The Belmont principle of justice requires equal treatment of all participants, which is not necessarily the same as equal payment. With drawings, each participant is treated equally in being given the same opportunity to win a prize.

Legal issues

HSD and the IRB cannot offer guidance about any legal issues or requirements associated with drawings.

Example: An undergraduate student researcher is recruiting 50 adults to take a 15-minute minimal risk online survey. There is no budget for the project, so the researcher proposes a drawing for a $25 gift card once all data have been collected.

Class credit

Researchers who are specifically recruiting students in their college, department, or courses may offer extra credit for participating in a study. This may be through a departmental subject pool/registry or by offering a research opportunity directly to students in a particular class.

Minimizing the possibility of undue influence

It is UW IRB policy that a non-research alternative must be offered to earn the same extra credit. The non-research alternative must not involve more time or risk than the research participation.

Other issues to consider

The researcher and the IRB should consider the possibility of coercion when a study is offered to a specific class, especially if researcher is the teacher. The circumstances should be managed so that students aren’t penalized for not taking part. This is typically accomplished by providing some way to keep the teacher/researcher from knowing who did or did not participate until after the course has been completed and grades have been assigned.

Example: A researcher asks an instructor colleague to recruit students from the instructor’s course to complete a one-time survey. The instructor agrees to offer students 5 extra credit points if they take the research survey. Students who do not want to participate in the research but wish to earn 5 extra credit points are offered an alternative activity that is estimated to take the same amount of effort as completing the research survey.

Token gifts of appreciation

These are items of low monetary value that are provided to thank subjects. While it is preferable to reimburse and compensate subjects for their participation in research, some budgets may only allow for small cash payments (discussed above) or modest appreciation gifts. Examples include but are not limited to: food (e.g., a candy bar), small toys, books, self-care items such as combs, and re-usable grocery bags.

Minimizing the possibility of undue influence

Because these are of low monetary value, the possibility of unduly influencing subjects to participate is low. However, there may be special considerations associated with specific subjects populations such as prisoners.

Other issues to consider

The cultural, and age appropriateness of the items should be considered. For example, items for infants or young children should be not be too small in size, have small removable parts, or made of materials that could be toxic if ingested (e.g., lead paint, or food with nuts that could be dangerous to children with nut allergies).

Example: Researchers are conducting a small pilot study for which they will recruit 20 children ages 5-9. Research procedures include brief interviews with the children and observing their play with other subjects. Researchers have only a small budget for this pilot work and propose providing a gift of crayons, stickers, and a book for each of the children.

Peer (“snowball”) recruitment incentives

Peer recruitment incentives are incentives provided to subjects who enroll in a research study for referring others as possible or actual participants in the same study. The UW IRB allows peer recruitment (with or without incentives) on a case-by-case basis.

Minimizing the possibility of undue influence

As with other types of subject payment, the permissibility of this method depends on whether the amount paid for each referral, as well as the total amount a subject may receive for peer recruitment, is appropriate given the subject’s time and effort. The IRB must also assess the potential for coercion or undue influence that the enrolled subject may direct against the individuals they attempt to recruit. Researchers should provide guidelines to peer recruiters in order to minimize this possibility.

Other issues to consider

This is an incentive for assisting researchers in conducting their research, rather than incentive for participation in the research as a subject. Depending on the study, it may raise significant privacy and confidentiality concerns that the researcher and IRB need to manage.


Must reimbursement be the same for all subjects in a study?

The actual amount reimbursed may be different for different subjects because the expenses they incur as a result of participation may differ (e.g., local transportation costs; a meal). The UW IRB expects a researcher to decide which specific out-of-pocket expenses will be reimbursed and to offer that reimbursement to all subjects who might incur those specific expenses. The key principle is that it should always be clear which specific costs will (or won’t be reimbursed). For example, it should be clear whether reimbursement of transportation expenses will apply only to local transportation or whether it will also include transportation from longer distances (e.g., gas and mileage, or airfare).

Must compensation be the same for all subjects in a study?

This is not a requirement, but the IRB will generally expect compensation to be the same for all research participants (regardless of individual earning potential) and to reflect the general value of the time and burdens associated with participation. The IRB will expect researchers to provide a justification for offering different compensation to different groups of subjects who participate in the same procedures.

Must incentives be the same for all subjects in a study?

This is not a requirement, but the IRB will generally expect incentives to be the same for all research participants who complete the same procedures, unless the incentive is offered through a drawing. The IRB will otherwise expect researchers to provide a justification for offering different incentives to different groups of subjects who participate in the same procedures. For example, in some circumstances it might be appropriate to consider differing incentives as one tool to help promote desired diversity in the study population.

Can participants donate payments back to the study?

Participants are not required to accept reimbursement, compensation, or incentives. Any unaccepted payments remain part of the study budget. There is no formal mechanism for providing participants with a receipt and tax write-off unless they receive payment and then donate it through an official University channel (which will be unlikely to directly benefit the study or the study investigator).

For UW employees, will payments be added to their paychecks? And will income tax be taken out of the payment?

Employees are considered to be on their own time when participating in research. This means that any payments are not part of the payroll and no taxes are taken out. Employees who receive $600 or more in research payments will receive a federal income tax Form 1099-MISC (which is also sent to the Internal Revenue Service), and they are responsible for paying taxes on the reported amount.

What is the IRB's responsibility with respect to collection of Social Security numbers (SSNs)?

See the discussion in “Payment information to provide as part of the consent process”. In summary, the IRB has no role for enforcing or advising about the collection of SSNs but it has an appropriate role in reviewing the researcher’s plan about whether SSN collection will be described in the consent process or form.

Are there any special concerns about payment for research participation through Amazon’s Mechanical Turk (MTurk)?

Mechanical Turk is commonly used for surveys and social/behavioral studies.

  • Pro-rating of payment is generally not possible.
  • UW employees, immediate relatives, and students involved in the immediate research are not eligible for payment via MTurk. In order to comply with fiscal accountability and conflict of interest, UW employees, immediate relatives, or students involved in the actual research must be screened out from participating in the MTurk task. See the UW Finance website for more information.
  • Attention checks. Researchers sometimes want to insert “attention check” questions or tasks, which can cause the rejection of the participant’s answers. This means that the participant might not be paid. Also, their reputation on the MTurk platform may be lowered, meaning they will qualify for fewer MTurk jobs (research or non-research) and might eventually be kicked off the platform. For this reason, researchers and the IRB should carefully consider whether attention checks are really necessary or whether any data clean-up can instead be done after data collection and distribution of incentives. Otherwise, it may be appropriate to state in the consent form that incentives are contingent upon correctly completing the attention checks. Some IRBs recommend consent language such as:

“Note: Only meaningful responses will be considered a completed survey. Meaningful responses are determined by successful completion  of the entire survey, reasonable completion time, and passing quality checks. Quality checks are questions in the survey that anyone can    answer correctly if thoughtfully reading the question. You must submit the HIT to receive compensation. Only submitted HITs with            complete responses, reasonable response time, and passing quality checks will be accepted. If you submit a HIT for a survey response that does not meet these requirements, your HIT will be rejected. If you are not compensated, please contact [name, contact information] to      receive a detailed explanation of why your data did not reach the standards.” (University of Tulsa consent language; October 2020)

Is profit-sharing with participants allowed as an incentive?

This is rarely a possibility and each case must be evaluated on its own merits. Issues to consider include: the timing and duration of profit-sharing, whether it is possible to estimate the value of the profit-sharing, how the profit-sharing is described, and whether the value may be so great as to be unduly influential.

Related Materials

UW Consent Templates

Regulatory References

  1. 45 CFR 46.166 [pre-2018 requirements] and 45 CFR 46.116a2 [2018 requirements]
  2. 45 CFR 46.305 [pre-2018 and 2018 requirements]
  3. OHRP, “Informed Consent FAQs”
  4. FDA, “Payment and Reimbursement to Research Subjects”, January, 2018
  5. SACHRP Recommendations, “Attachment A – Addressing Ethical Concerns Regarding Offers of Payment to Research Participants”, October 18, 2019
  6. Christopher et al., Enrolling in Clinical Research While Incarcerated. What Influences Participants’ Decisions? Hastings Center Report 47(2): 21-29. 2017
  7. Copes et al., Inmates’ Perceptions of the Benefits and Harm from Prison Interviews. Field Methods 25(2): 182-196. 2012
  8. Cryder et al, Informative inducement: Study payment as a signal of risk. Social Science & Medicine 70: 455-464. 2010.
  9. Field & Berman, Ethical Conduct of Clinical Research Involving Children. Institute of Medicine (US) Committee on Clinical Research Involving Children. 2004
  10. Gelinas et al., A Framework for Ethical Payment to Research Participants. The New England Journal of Medicine 378(8): 766-771. 2018
  11. Halpern et al., Empirical Assessment of Whether Moderate Payments are Undue or Unjust Inducements for Participation in Clinical Trials. The Archives of Internal Medicine 164: 801-803. 2014
  12. Largent & Fernandez Lynch, Paying Research Participants: The Outsized Influence of “Undue Influence”. IRB 39(4): 1-9. 2017
  13. Ravi et al., Financial Payments for Participating in Research while Incarcerated: Attitudes of Prisoners. IRB Ethics and Human Research 40(6): 1-6. 2018
  14. Smoyer et al., Compensation for Incarcerated Research Participants: Diverse State Policies Suggest a New Research Agenda. American Journal of Public Health, Commentaries 99(10): 1746-1752.

Version Information

Open the accordion below for version changes to this guidance.

Version History

Version Number Posted Date Implementation Date Change Notes
1.3 03.24.2024 03.24.2024 Revise Privacy and Confidentiality section to list information that will be listed in Workday and describe who will have access
1.2 08.26.2021 08.26.2021 Add note to review UW Financial Management website re: subject payment tax reporting
1.1 11.23.2020 11.23.2020 Addition of Researcher Quick Guide
1.0 11.02.2020 11.02.2020 Guidance newly posted

Keywords: Subject payment