“Participant payment” and “sponsor payment” are frequently confused, but they are two different money flows governed by different rules. This guide covers payments to research participants — the compensation and reimbursement a clinical trial sponsor or site pays directly to the individuals enrolled in a study, for their time, burden, and expenses. It does not cover per-patient site fees, investigator grants, or other sponsor-to-institution payments negotiated in a clinical trial agreement; those are a distinct budgeting and contracting topic, addressed briefly at the end of this guide so the two aren’t conflated.
Participant payment sits at the intersection of research ethics and tax administration. An Institutional Review Board (IRB) or Research Ethics Committee (REC) has to evaluate whether a proposed payment plan could function as an undue influence on a prospective participant’s decision to enroll or to stay enrolled, while the institution or sponsor issuing the payment has to track it correctly for federal tax reporting. Both obligations attach to the same line item in a protocol budget, which is why they’re covered together here.
Why participants are paid at all
US federal guidance treats payment to research participants as a normal, generally acceptable recruitment and retention practice — not a benefit of the research itself. The FDA’s guidance Payment and Reimbursement to Research Subjects (issued January 2018) states plainly that paying research subjects in exchange for participation is common and, in general, acceptable, but that payment is not considered a benefit of the research when an IRB weighs risks against benefits during protocol review — it’s a recruitment incentive, evaluated separately.
That distinction matters operationally. Because payment isn’t counted as a benefit, it can’t be used to justify exposing participants to greater risk than the science warrants — a poorly designed, high-risk study doesn’t become acceptable because participants are paid well to join it. Payment is reviewed on its own terms, specifically for whether its amount, timing, and method could distort a prospective participant’s judgment about whether to enroll.
Payment vs. reimbursement — not the same category
The FDA guidance and most institutional policies draw a line between two categories of money that often appear on the same payment schedule but are treated differently:
- Reimbursement covers a participant’s actual out-of-pocket costs of taking part — travel to the site, parking, lodging for a multi-day visit, and comparable expenses. FDA’s guidance is explicit that reimbursement for reasonable travel and lodging expenses does not, by itself, raise undue-influence concerns, because it’s restoring the participant to a neutral financial position rather than offering a net incentive.
- Payment (sometimes called compensation) covers everything paid beyond cost recovery — for the participant’s time, inconvenience, discomfort, and the burden of study procedures. This is the category IRBs scrutinize, because it’s the part capable of functioning as an inducement rather than a wash.
Protocols and consent documents that lump both into a single undifferentiated “payment” line make IRB review harder and can obscure whether the compensation component alone is proportionate. Separating the two in the budget and in the consent form is standard practice.
Undue influence and coercion: the ethical concern that shapes everything else
The regulatory concept doing the most work in this area is undue influence — distinct from coercion, though the two are often discussed together. Coercion involves an explicit or implicit threat; undue influence involves an offer so large, or structured in a way, that it overrides a person’s ordinary capacity to weigh risk and decline to participate. Federal human-subjects regulation requires that consent be sought under circumstances that minimize the possibility of coercion or undue influence (45 CFR 46, the Common Rule, §46.116(a)(1); the parallel FDA requirement appears at 21 CFR 50.20).
HHS’s Office for Human Research Protections (OHRP) and its advisory committee, SACHRP, have written specifically on how this applies to payment. OHRP’s guidance recognizes that paying research participants is common and generally acceptable, but instructs IRBs to be sensitive to whether any aspect of a proposed payment plan could function as an undue influence that interferes with a prospective participant’s ability to give voluntary informed consent — and notes that because influence is contextual, the same payment offer can affect different individuals differently depending on their financial circumstances. SACHRP’s recommendations to OHRP (Attachment A: Addressing Ethical Concerns Regarding Offers of Payment to Research Participants) go further, arguing that concerns about payment size can be managed through study design and oversight rather than by simply capping or minimizing payment amounts — a shift away from treating “higher payment = higher risk” as an automatic rule.
In practice, this means an IRB isn’t asking “is this payment too generous?” in the abstract. It’s asking whether the amount, and especially the structure of disbursement, could push a specific population — people with limited income, people who are unemployed, people facing a medical bill — toward accepting risks they would otherwise decline, or toward staying in a study past the point they’d otherwise want to withdraw.
Payment structures: per-visit, prorated, lump-sum, and milestone-based
How a payment is broken up across the course of a study is, in FDA’s and OHRP’s framing, at least as important as the total amount. Four structures come up repeatedly in protocols:
- Per-visit payment. A fixed amount is paid at each study visit, tied to attendance and completion of that visit’s procedures. This is the structure regulators view most favorably, because it compensates burden as it’s actually incurred and doesn’t penalize a participant who withdraws partway through — earned payment for visits already completed is retained regardless of whether the participant finishes the study.
- Prorated/accruing payment. Functionally similar to per-visit payment: credit for payment accrues progressively as the study proceeds, even if it’s disbursed periodically (e.g., monthly) rather than at every single visit. FDA’s guidance specifically recommends this approach for studies of meaningful duration or with multiple visits.
- Lump-sum payment at enrollment. Paying the full amount upfront, before study procedures occur, raises the opposite concern from completion-based payment — it can function as an inducement to enroll in the first place, independent of the participant’s actual willingness to undergo what the study involves, and it leaves the sponsor with no mechanism to withhold payment already made if a participant is later found ineligible or withdraws immediately.
- Milestone- or completion-based payment. A structure where some or all payment is contingent on reaching a milestone — most concerningly, completing the entire study. This is the structure both FDA and OHRP guidance treat as a genuine, documented ethical concern, not a hypothetical one: making the entire payment contingent on completing the whole study creates pressure to stay enrolled — including to forgo withdrawal — specifically because leaving early means forfeiting money already, in effect, earned through participation to that point. That directly conflicts with a participant’s regulatory right to withdraw from a study at any time without penalty.
FDA’s guidance addresses this directly: any credit for payment should accrue as the study progresses and should not be contingent upon the subject completing the entire study. A small completion bonus — a modest additional amount paid on finishing, on top of an already-accrued per-visit or prorated total — is acceptable to FDA provided it isn’t itself coercive, meaning it shouldn’t be so large relative to the accrued base payment that it becomes the dominant reason to stay enrolled. The dividing line FDA draws is between a small completion incentive layered on top of fair, already-accrued compensation, and a payment structure where withdrawal means losing most or all of what’s owed.
OHRP’s guidance reinforces the same principle from the informed-consent side: for studies of considerable duration or with multiple interactions, payment should be prorated for time already participated rather than delayed until study completion, precisely because delayed lump-sum payment can unduly influence a participant’s decision to exercise the right to withdraw. This point is the single most consistently repeated recommendation across FDA and OHRP guidance on payment structure, and it’s the first thing an IRB reviewing a payment schedule is likely to check.
Tax treatment: 1099 reporting for participant payments
Payments to research participants are taxable income to the recipient, and — because participants are treated as non-employees receiving compensation, not wage-earners — institutions and sponsors report them the way they report other non-employee payments: on Form 1099, with a Form W-9 collected in advance to obtain the participant’s taxpayer identification number.
The dollar threshold that triggers a mandatory 1099 has changed for 2026. For calendar years through 2025, the long-standing threshold for issuing a Form 1099-MISC/1099-NEC to a non-employee was $600 in aggregate payments per payer per calendar year — the figure still reflected in many institutional human-subjects-payment policies. Section 70433 of the One Big Beautiful Bill Act (P.L. 119-21, signed into law July 4, 2025) raises that general 1099-MISC/1099-NEC reporting threshold to $2,000, effective for payments made starting in the 2026 calendar year, with the figure indexed for inflation beginning in 2027. This is a general change to non-employee-compensation reporting across the tax code, not a clinical-trial-specific rule, but it applies directly to participant payments because most institutions issue them as 1099-MISC “other income.”
A few points research administrators and IRBs should keep straight when applying this:
- The threshold only governs when a 1099 must be issued — it does not change what’s taxable. A participant who receives $1,500 in a calendar year, under the 2026 threshold, won’t receive a 1099 for it, but that income remains fully taxable and reportable by the participant regardless of whether a form was issued.
- Reimbursements for actual expenses (travel, parking, lodging) are generally treated differently from compensation for time/burden for tax purposes, in the same way they’re treated differently for undue-influence review — accountable-plan-style expense reimbursement isn’t the same category as taxable compensation, though institutions should confirm this with their own tax counsel rather than assume it categorically, since treatment can depend on documentation and whether the institution operates an accountable reimbursement plan.
- Institutional W-9 collection practices built around the old $600 threshold need updating for 2026 — a site that continues collecting W-9s and preparing 1099s at $600 isn’t doing anything wrong, but it’s applying a stricter internal standard than the law now requires, which may be a deliberate institutional choice (e.g., simplifying recordkeeping by not tracking two thresholds) rather than a compliance necessity.
- Because this is a mid-2026 statutory change, institutional finance offices and payment-processing vendors were still updating internal policy documents and W-9/1099 workflows as of this writing — verify current institutional policy rather than assuming it already reflects the new threshold.
None of this is IRB business as such — an IRB doesn’t review tax withholding — but the payment schedule the IRB approves is exactly the data a research office needs to determine which participants will cross the reporting threshold in a given year, so the two functions have to coordinate on the same numbers.
IRB review of payment plans as part of protocol approval
Payment isn’t a side administrative detail cleared separately from the protocol — FDA and OHRP guidance both treat it as a required element of the initial IRB submission and ongoing review, alongside risk, benefit, and consent language. In practice, an IRB/REC review of a payment plan typically covers:
- Amount. Whether the total payment, and its per-visit breakdown, is proportionate to the time, burden, and discomfort actually involved — not simply whether it’s “high” or “low” in absolute terms, since burden and local economic context both factor in.
- Structure and timing. Whether payment accrues progressively (favored) or is disproportionately back-loaded toward study completion (the structure that draws the most scrutiny, per the previous section).
- Disclosure in the consent document. FDA guidance requires that the amount and schedule of all payments be set out in the informed consent document itself — not referenced separately or left to a recruitment flyer — so a prospective participant can evaluate the payment terms as part of the same decision they’re making about risk and benefit.
- Population-specific sensitivity. Whether the study population includes people for whom a given payment amount is more likely to function as an undue influence — for example, populations with limited income, or populations facing significant out-of-pocket costs related to their condition — which may call for additional IRB scrutiny of the same payment plan that would draw no comment for a different population.
- Consistency with withdrawal rights. Whether a participant who withdraws mid-study retains payment already accrued for procedures already completed, consistent with the general principle that withdrawal shouldn’t be financially penalized.
Because payment plans are part of the protocol package IRBs review at initial approval, changes to a payment schedule during a study — a sponsor increasing payment to boost lagging enrollment, for instance — typically require submission as a protocol amendment for IRB review before implementation, not a unilateral operational change, precisely because a change in payment can change the undue-influence calculus the IRB already evaluated once.
Participant payments vs. sponsor-to-site payments
It’s worth being explicit about what this guide does not cover, because the terminology overlaps. A clinical trial also involves payments the sponsor makes to the investigator site or institution — per-patient visit fees, IRB fee reimbursement, and other budget line items negotiated in the clinical trial agreement between sponsor and site. Those payments compensate the site’s staff time, facilities, and regulatory overhead for running the trial; they are a contracting and research-administration budgeting matter, governed by the clinical trial agreement rather than by IRB undue-influence review, and the money generally never passes through to individual participants.
Participant payment, by contrast, is money that moves from the sponsor or site directly to the individual enrolled in the study, in exchange for that individual’s time and participation — and it’s this payment, not the sponsor-to-site budget, that undue-influence review, informed-consent disclosure requirements, and 1099 reporting all apply to. Keeping the two separate in protocol documentation avoids a common source of confusion during both IRB review and audit.
Frequently asked questions
Is paying research participants ethical?
Yes, under the framework FDA and OHRP apply — payment is treated as a legitimate, generally acceptable recruitment and retention practice, not an ethical problem in itself. The ethical scrutiny is targeted specifically at whether a given payment’s amount and structure could function as an undue influence for a specific population, not at the practice of paying participants generally.
Can a participant be paid more for a riskier study?
Payment can reflect greater time commitment or burden associated with a riskier or more demanding protocol, but FDA guidance is explicit that payment is not weighed as a benefit against the study’s risks during IRB review — a study’s risk-benefit balance has to stand on its own scientific and clinical merits, independent of how well participants are compensated for taking part.
Does travel reimbursement count toward the taxable/reportable payment total?
Reimbursement for reasonable travel and lodging expenses is generally treated as expense recovery rather than taxable compensation, distinct from payment for time and burden — but institutions should confirm the specific tax treatment with their own finance/tax office, since correct handling depends on documentation and how the reimbursement is administered.
What happens to a participant’s payment if they withdraw from a study early?
Under the payment structures FDA and OHRP guidance favor, a participant who withdraws retains payment already accrued for study visits and procedures already completed — withdrawal shouldn’t mean forfeiting compensation already earned. This is precisely why fully completion-contingent payment structures are discouraged: they create financial pressure against exercising the right to withdraw.
Who decides how much participants get paid — the sponsor or the IRB?
The sponsor or investigator proposes the payment amount and structure as part of the protocol; the IRB reviews and must approve it, specifically checking for undue-influence and disclosure concerns, before enrollment can begin. Changes to the payment plan during the study generally require IRB review as a protocol amendment.
