Payments for Reimbursement, Compensation & Incentives

Payments for research participation can be classified into the following categories:

(Out-of-Pocket Expenses)
(Time & Effort)
(For Participation)
Definition Payment to offset expenses incurred as a result of participation Payment for time and effort, and acceptance of research-related burdens. Payment in excess/beyond what is needed to reimburse or compensate.
Purpose To remove financial barriers to participation; and restore participants to their pre-participation financial state by covering reasonable out-of-pocket expenses (e.g., transportation, childcare). To acknowledge the participant’s contributions by placing it in the context of payment for similarly burdensome activites outside research, such as work.
Compensation can be monetary (cash, voucher, gift cards etc.) or non-monetary (course credits, gifts etc.).
To encourage research recruitment and retention by: making participation relatively more attractive to subjects; and increasing their willingness to accept research uncertainty and reasonable research-related risks.
Example Reimbursing the cost of taking a taxi for the study visit. Paying $10 for the 1 hour required to complete the research interview. Offering $300 as a completion bonus.
Undue Influence? No
Gives no independent reason for an individual to be influenced to participate.
Gives no independent reason for an individual to be influenced to participate.
Incentives have the potential to distort judgement and introduce undue influence^.
Ethical Default? Yes
Reimbursement treats participants fairly & is desirable.
Compensation treats participants fairly & adequately recompenses them.
Generally not favoured or encouraged
Incentives goes beyond what fairness requires.

^Permissibly of incentives is context-dependent and must be justified. If deemed ethically permissible for a study, the amount should be reasonable and does not unduly influence participation.


Payment for participation in research can raise ethical concerns if it interferes with a person’s decision-making ability for informed consent. If the payment presents an undue influence for participation, it can undermine a subject’s capacity to give true voluntary informed consent, and is thus unethical.


 Undue Influence

“Undue influence … occurs through an offer of an excessive, unwarranted, inappropriate or improper reward or other overture in order to obtain compliance” (US National Commission, 1979).

Undue influence arises when the payment is significant enough to impair or distort a person’s ability to make a reasonable decision – e.g., takes on research-related risks s/he would not have otherwise accepted; or participates in an activity that is contrary his/her own values, beliefs, or interests. The subject should be able to appropriately assess the risks and benefits of participation, and not be induced by the payment to participate.


Amount & Type of Payment

Therefore, when considering payments for participation, researchers should take undue influence into account, as well as the economic status and resources of participants. The amount and type of payment should be reasonable and commensurate with the time and effort required (and burdens assumed) for study participation, and should not be excessive that it unduly influences their judgement to participate.

 When determining the appropriate amount, consider factors like the: research nature and duration of participation, level of risk(s) involved, potential burden(s) on the subject, and prevailing rates in the field. Payment rates should not be based on an individual’s earning potential outside of research.


Payment Schedules

Information on the payment structure – including amount, timing, terms, and type (e.g., cash, voucher, course credits) – should be provided in the IRB application, and clearly communicated in the informed consent form to avoid disputes with subjects. The details should also cover the event where a subject decides to withdraw during the study.

 For studies that involve extensive participation (e.g., a 4-hour battery of assessments) or longitudinal/multi-visit research (e.g., requiring two or more study visits), total payment should not be contingent upon completion of the entire study. This may unduly influence a subject’s ability to exercise their right to voluntarily withdraw at any time.

 In such scenarios, it is recommended that payment be:

  • Pro-rated in a manner proportionate to the time & effort given; and/or (e.g., A $40 compensation for a 4-hour study visit: a pro-rated amount of $20 for the subject who withdraws after 2 hours)    
  • Partial and given at the end of each study visit. (e.g. A $300 reimbursement & compensation for 6 study visits at NTU: a partial payment of $50 at the end of each study visit, rather than a lump sum of $300 at the conclusion of the study at the final visit).    


Advertising Payments

Study advertisements may state that ​participants will be paid, but it should not emphasize the payment or the amount to be paid. Please refer to our guidelines here for more details.



  • Brown J.S., & Largent E.A. (2021) Payment of Research Subjects. Institutional Review Board: Management and Function (3rd ed.), 877-888
  • Gelinas, L. et al. (2018a) A Framework for Ethical Payment to Research Participants. New England Journal of Medicine, 378(8), 766-771.
  • Langert E.A.(2022, December) Undue Influence & the Good Influence of IRBs. Presented at the 2022 Public Responsibility in Medicine & Resaerch (PRIM&R) Annual Conference.



To facilitate PI's payments to research participants, NTU Corporate PayNow is now available for payments to your recruited participants.

PIs are advised to collect participants' mobile numbers instead of NRIC numbers to facilitate payments. Please note that supporting documentation (e.g. signed consent forms) are required. 

To raise a payment via Corporate PayNow to individuals, please do so through ServiceNow.
For more information, please refer to the knowledge article in ServiceNow.
Payment-related queries:  Ask P2P@NTU