How much should I pay participants?
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Our minimum rate is £6 / $8 per hour. Everything beyond that is your call. We recommend paying at least £9 / $12 per hour, but the right amount is yours to decide based on your study.

Payment affects how quickly you recruit and the quality of the responses you get, because participants choose between studies partly based on reward. So it's worth weighing the factors that matter for your research: the effort involved (more time-consuming, complex, or cognitively demanding tasks should be paid more, even if they're short) and who you're targeting (a specific or hard-to-reach population, or people in well-paid professions, will usually need a higher reward to recruit well).

During setup, you will also see a competitive pricing rate, which is optional guidance showing how your reward compares to what your target audience typically sees. It's there to inform your decision, but the call is up to you.

Does each participant’s pay change with the time they take to complete the study?
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No. The base reward is fixed at the amount you set, so every participant receives the same payment regardless of how long they take to complete your study. The reward per hour you see during setup is simply that fixed amount expressed as an hourly rate, based on your estimated completion time; it's a guide for you and for Prolific, as it allows us to calculate the minimum payment.

The time itself doesn't change anyone's pay, but if people consistently take much longer than you estimated, your study can fall below the minimum hourly rate and be flagged as underpaying. In that case, you’ll need to adjust your payment. This is why estimating your completion time accurately matters.

If participants finish faster than expected, am I charged less/refunded?
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No. Because the base reward is fixed, each participant who completes your study is paid the full amount you set, whether they finish quicker or take more time. So, a fast study doesn't lower your per-participant cost or trigger a refund.

That being said, you're only charged for the places you actually fill. When you publish, Prolific reserves the funds to cover your full sample, but if you stop a study before it's complete, any funds reserved for places you didn't recruit are returned to your workspace balance automatically. Unused balance stays in your workspace for future studies, or you can request a refund from Support if you'd rather have it back.

Do I have to pay participants who failed attention checks, sped, or were flagged as low-authenticity?
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By default, you approve and pay anyone who completed your study and provided data, but you can reject a submission and not pay the participant if it meets Prolific's rejection criteria. Failed attention checks, exceptionally fast completion, and failed authenticity checks can all be valid grounds, but each comes with specific conditions, and getting them wrong unfairly penalises participants.

Before rejecting, check the exact rules in the "Who should I reject?" article, which lists every valid and invalid reason. Keep rejections to a minimum and review each submission in context.

Do I have to pay participants who were screened-out?
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Yes, but only partially. Anyone who's screened out of your study must be paid for their time; this is built into how screening works on Prolific and isn't optional. If you use custom screening, you set a fixed screen-out reward during setup (minimum £0.10 / $0.14), and screened-out participants are automatically approved and paid that amount. Those payments are included in your upfront study cost, and any screen-out budget you don't use is returned to your balance when the study is complete.

If you screened people out without using the custom screening feature, the obligation to pay still applies; you just have to handle it manually. In that case, you must pay each screened-out participant a bonus equivalent to the screen-out reward they'd otherwise have received (£0.10 / $0.14), so nobody who completed your screener goes uncompensated.
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Do I have to pay participants who returned or timed out?
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No. A returned submission means the participant didn't complete your study, so it carries no payment and the spot reopens automatically for someone else. A timed-out submission means they didn't finish within the allowed time; these are excluded from your totals and aren't charged; the spot also reopens automatically for someone else. Neither affects the participant's standing on Prolific.
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How does payment work for longitudinal / multi-wave studies?
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Each wave is paid separately, as its own submission. The key rule is that every individual wave must meet the minimum rate of £6 / $8 per hour on its own; you can't average an underpaying wave against a higher one.

In Prolific's longitudinal setup, a participant has to complete a wave and have that submission approved before they become eligible for the next one. Prolific handles eligibility automatically based on who's been approved, so you don't manage allowlists yourself, but it does mean you need to approve each wave promptly to keep participants moving through to the next one.

Be upfront in your study description about the full structure and the pay across all waves, especially if a final payment or bonus depends on completing everything; participants should be able to make a fully informed decision before wave one. If you've designed a bonus for completing all waves, you can state that as an incentive from the start.

Can I change how much my study pays after it’s live?
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Not freely. Once a study is published, you can only increase the reward in cases where your study is underpaying. If your study's average reward per hour falls below the minimum, Prolific will prompt you to make adjustment payments to bring it back up. That's the one situation where raising pay on a live study is built in.

If what you actually want is to pay more across the board, not because the study is underpaying but because you've decided the reward should be higher, you can't edit the live study to do that. The workaround is to stop the current study and duplicate it as a new one with the higher reward, then recruit from there. You can also use bonus payments to give individual participants extra on top of their base reward at any point.

Do bonuses count toward the minimum required hourly pay?
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No. Bonuses sit on top of the base reward; they're additional payments, not part of how Prolific calculates your minimum hourly rate. Your study has to meet the £6 / $8 per hour minimum through the base reward alone, and a bonus can't be used to top a low base reward up to the minimum. The same goes for raffle or lottery payments: those have to be extra, on top of the minimum reward everyone receives.

Can I use bonuses to fix a study flagged as underpaying?
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Bonuses aren't the intended tool for this; the proper fix is the dedicated "Adjust reward per hour" option, which raises pay to the minimum and is built specifically to resolve underpaying. That's the route to use.
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If you do reach for bonuses instead, two things have to be true for it to actually work. First, the bonus must be paid against the Submission ID, not the Prolific ID; otherwise the payment won't be associated with the submission and your study's reward-per-hour won't update.
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Second, you have to pay the bonus to every participant, not just some. Because the underpaying flag is based on the study's overall reward-per-hour, bonusing only a portion of participants won't lift the average, and the study will stay flagged.

In short, use the adjustment payment feature to fix underpaying. If you use bonuses, they must be paid by Submission ID and to all participants, or the fix won't take.

I want to pay a participant who was returned or timed out. How do I do it?
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Use a bonus payment; that's the route for paying anyone whose submission isn't in the normal "approve and pay" flow.
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A participant counts as eligible for a bonus as long as they've taken part in a study of yours, so a returned or timed-out submission doesn't block you from issuing them a bonus. You can do this from your submissions list: select the participant and use the "Bonus pay" option, or pay in bulk via Bulk actions using their Submission ID.

You'll need available balance to cover it, on top of what's reserved for the study. If you don’t currently have enough available balance, but are expecting your study to cost less than what’s reserved for it, you can wait until your study is marked as complete and the unused funds are returned to your balance to issue the bonus payment.
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Bonuses are sent straight to the participant and can't be refunded, so double-check the amount before sending.

My study is flagged as underpaying, how do I fix it?
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Use the "Adjust reward per hour" option on your study's submissions page. It lets you bring pay back up to either the minimum rate or your initial reward per hour. The option appears once at least one submission is approved or 50% of places are filled. You may need to top up your balance to cover the adjustment, since it wasn't part of your original study cost.
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For the full step-by-step, see "How do I resolve underpaying studies?”

Bonus troubleshooting
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How do I know if a participant was paid?
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The submission status tells you. Once you approve a submission, it moves to the "Approved" tab, and approved means paid; payment is processed at the point of approval, so there's no separate step to confirm. Anything still in "Awaiting review" hasn't been paid yet; it's waiting on your decision (and will auto-approve and automatically pay at 21 days).

For bonuses, the payment is reflected in the participant's "Reward" column in your study summary rather than shown separately, and it can take a little time for the summary to update after you send it.

If a participant tells you they haven't received a bonus you've sent, it's worth checking the status has finished processing before assuming something went wrong.