Quick answer: If you have already submitted the month's payroll and CPF and then realise a bonus was missed, do not reopen or amend the closed run. CPF is payable based on when wages are actually paid — not the period they relate to — so add the bonus to your next payroll run. There it is treated as an Additional Wage, CPF is calculated automatically, and it flows into that month's CPF submission and payslip. The only exception is if you already paid the bonus cash inside the closed month, in which case CPF was due then and you make a supplementary CPF eZpay submission for that month.
It is a common moment of panic for a small-business owner or finance admin: the month's payroll run is done, CPF has been submitted, everyone has been paid — and then you remember a bonus you meant to include. The instinctive move is to reopen the closed month and slot the bonus in. That instinct is wrong, and most payroll systems (AimmPayroll included) will not let you do it anyway — a submitted run is locked.
The good news is that Singapore's CPF rules make this genuinely easy to fix, without amendments or unlocking anything. This guide explains the one rule that solves it, the exact steps in AimmPayroll, and the single exception where you do need to correct the earlier month. For how CPF treats bonuses in general, see our AWS and 13th-month bonus guide.
Why you should not reopen the closed month
Once a payroll run is submitted, three things are already fixed for that month: the CPF file has gone to CPF Board, the itemised payslips have been issued, and (usually) the salaries have been paid. Editing that run after the fact would put your records out of step with what CPF Board and your employees actually received — the opposite of a clean audit trail.
That is why AimmPayroll locks a submitted run. You will see a clear locked notice on the run, and the app points you to the next month's run instead. (Deleting or editing a run is only possible while it is still in draft or calculated status, before submission.) This is a feature, not a limitation: it keeps your payroll history trustworthy. And as the next section shows, you do not need to touch the closed month at all.
The rule that makes this easy: CPF follows when wages are paid
Here is the principle that resolves the whole problem:
CPF contributions are payable based on when wages are actually paid to the employee — not the period the wages relate to.
So a bonus you pay in August belongs in August's CPF submission, even if it rewards work done in July. You are not "backdating" anything and you are not correcting July. You are simply paying the bonus now, in the current open month, and letting it attract CPF in that month.
This is the same reason bonuses and the Annual Wage Supplement are always reported in the month they are paid rather than the month they are earned — a December bonus sits in December's submission even though it reflects the whole year. Because of this rule, a forgotten bonus is a carry-forward, not an amendment. No unlock, no restating a closed month, no correction file. You can confirm the current position with CPF Board.
Additional Wage vs Ordinary Wage (and the AW ceiling)
A bonus is an Additional Wage (AW) — a one-off payment such as a bonus, the Annual Wage Supplement, or leave encashment. It is different from Ordinary Wages (OW), which are your regular monthly salary.
The distinction matters for CPF ceilings:
| Ordinary Wages (OW) | Additional Wages (AW) | |
|---|---|---|
| What it is | Regular monthly salary | Bonus, AWS, leave encashment |
| CPF ceiling | Monthly OW ceiling (S$8,000/month from 2026) | Annual AW ceiling |
| Reported | In the month earned | In the month paid |
The Additional Wage ceiling limits how much of an employee's bonuses attracts CPF in a year:
AW ceiling = S$102,000 − total Ordinary Wages subject to CPF for the year.
In practice, CPF on bonuses is capped only once an employee's total wages for the year reach the S$102,000 annual ceiling. For the full mechanics see our AWS and 13th-month bonus guide, and for the monthly OW cap see the CPF Ordinary Wage ceiling 2026 guide. AimmPayroll applies both ceilings automatically, so you do not have to track them by hand.
Step-by-step: add the missed bonus in AimmPayroll
Because the bonus belongs in the current month, the fix lives entirely in your next run:
- Open next month's payroll run. Leave the closed, submitted run untouched — its locked notice is doing its job.
- Add the bonus to the employee. Use an Ad-hoc Payroll Item (or the Bonus calculator) on that employee's line.
- Label it "Bonus" and keep it CPF-able. Ad-hoc items carry per-item CPF and income flags; a bonus should have the CPF flag on so it is treated as an Additional Wage.
- Let CPF compute automatically. AimmPayroll works out the employer and employee CPF on the bonus as AW, against the Additional Wage ceiling, with the correct age-band and PR rates.
- Submit the run as normal. The bonus is included in that month's CPF eZpay file and itemised on the employee's payslip — nothing about the earlier month changes.
That is the whole fix. The employee sees the bonus clearly on their payslip, the CPF is correct, and your closed month stays intact. For the wider monthly sequence this sits inside, see how to run Singapore payroll.
The one exception: cash already paid in the closed month
There is a single situation where the current-month fix does not apply: if you already physically paid the bonus cash in the closed month — for example, a separate bank transfer done in July, outside payroll — then, under the "when wages are paid" rule, CPF on that bonus was due with that same month, not the next one.
To correct this calmly:
- Make a supplementary (additional) CPF submission for that earlier month through CPF eZpay, covering the extra Additional Wage that was paid.
- Because the contribution is going in after that month's due date, late-payment interest may apply — currently 1.5% per month, per CPF Board — on the shortfall.
- Keep the supplementary submission and payment records alongside the original run so the month reconciles.
This is uncommon for SMEs that pay everything through payroll, but worth knowing. See the CPF eZpay submission guide for how supplementary submissions and interest work, and check current figures with CPF Board.
Common mistakes to avoid
- Trying to "unlock" or edit the submitted month. It is locked by design; the fix belongs in the next run.
- Restating the earlier month's CPF when the cash was never paid then — that creates a mismatch with what CPF Board already received.
- Turning the CPF flag off on the ad-hoc bonus item, which would wrongly exclude it from CPF as an Additional Wage.
- Forgetting the exception: if the cash really did leave in the closed month, do make the supplementary submission for that month rather than carrying it forward.
How AimmPayroll handles a missed bonus
AimmPayroll is built around exactly this scenario. A submitted run shows a clear locked notice so you cannot accidentally corrupt a filed month, and it points you to the next run. There you add the bonus as an ad-hoc Additional Wage, and the app handles the CPF automatically — correct age-band and PR rates, the OW and AW ceilings, and inclusion in that month's CPF eZpay file and payslip. No manual workarounds, no spreadsheet corrections. Start free for up to three employees, or see pricing.
Frequently asked questions
I forgot a bonus after submitting CPF for the month. Do I need to amend the submission?
In almost all cases, no. CPF is payable based on when wages are actually paid, not the period they relate to. So you simply pay the bonus in your next payroll run, where it is treated as an Additional Wage and flows into that month's CPF submission. There is no need to reopen the closed month, unlock the run, or restate the earlier month.
Which month's CPF does a late bonus belong to?
The month you actually pay the bonus, not the month the work relates to. A bonus paid in August belongs in August's CPF submission even if it rewards July's performance. This is why a missed bonus is easy to fix — you carry it forward rather than backdating it.
What if I already paid the bonus cash to the employee inside the closed month?
Then CPF on that bonus was due with that same month, because the wages were paid then. Make a supplementary (additional) CPF submission for that month through CPF eZpay to cover the extra Additional Wage. Because it is being paid after the due date, late-payment interest — currently 1.5% per month per CPF Board — may apply. Keep the corrected records with the original run.
Can I reopen or edit a payroll run I have already submitted?
No. AimmPayroll locks a run once it is submitted, so the figures always match what CPF Board and your employees received. The app shows a clear locked notice on a submitted run and directs you to the next run, where you add the missed bonus as an Additional Wage. This protects your audit trail rather than quietly rewriting history.
Summary
A bonus you realise you missed after submitting the month is not the emergency it feels like. CPF follows when wages are paid, not the period they relate to, so the normal fix is to add the bonus to your next payroll run as an Additional Wage — CPF is computed automatically and the bonus lands in that month's CPF eZpay file and payslip, leaving the closed month untouched. The only exception is a bonus whose cash was already paid inside the closed month: there, CPF was due then, so you make a supplementary CPF eZpay submission for that month and may incur late-payment interest. For the underlying treatment, see our AWS and 13th-month bonus guide, the CPF eZpay submission guide, and how to run Singapore payroll.
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