Quick answer
- Week 1 or Month 1 means payroll treats each payday separately instead of accumulating pay, credits and bands from 1 January.
- The ordinary period share of credits and bands can still apply, so non-cumulative treatment is not the same as having no credits.
- Unused credits and bands from an earlier pay period do not help a later payday while Week 1/Month 1 applies.
- Revenue says payroll cannot make a backdated Income Tax or USC refund until a cumulative certificate/RPN is issued.
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On this page
Cumulative, Week 1 and Emergency basis compared
| Basis | How payroll looks back | Credits and bands | Refund effect |
|---|---|---|---|
| Cumulative | Uses pay and tax from 1 January to the current payday | Unused year-to-date amounts can carry within the same year | Payroll can correct an overpayment when the cumulative RPN supports it |
| Week 1 / Month 1 | Treats each payday on its own | Only that period’s share is used | No backdated payroll refund until cumulative treatment is issued |
| Emergency | Used when normal Revenue instructions are unavailable | Emergency bands/rates and no normal credits | Correct the employment/RPN first |
How non-cumulative PAYE works
For a single employee with €4,000 annual credits and a €44,000 annual band, the ordinary weekly share is about €76.93 of credits and €846.16 of band. On Week 1 basis, payroll applies only those weekly amounts to that week’s pay. It does not bring forward unused amounts from a week with little or no pay.
On cumulative basis, payroll compares cumulative pay, cumulative tax and cumulative entitlements from 1 January, allowing earlier unused amounts to affect the current result.
Worked example: variable weekly pay
Assume a single employee has no pay in Week 1 and earns €1,200 in Week 2, with the standard €44,000 band and €4,000 credits. This simplified example covers PAYE only.
| Week 2 calculation | Week 1 basis | Cumulative basis |
|---|---|---|
| Band available | €846.16 | €1,692.32 for two weeks |
| Credits available | €76.93 | €153.86 for two weeks |
| Gross tax | €310.77 | €240.00 |
| PAYE after credits | €233.84 | €86.14 |
The €147.70 difference comes from the unused Week 1 band and credit being available under cumulative treatment. Real payroll uses the exact RPN, dates and rounded year-to-date figures.
Why Revenue may use Week 1 basis
Week 1 basis can be used where Revenue does not want a change backdated through the earlier payroll year—for example, after some mid-year adjustments or a new allocation between employments. It can also appear where Revenue needs more information before authorising cumulative treatment.
The basis itself does not prove that payroll made an error. It is a signal to check the TCC, the reason for the Revenue instruction and whether an end-of-year return will be needed.
What to do if your payslip says Week 1 or Month 1
- Confirm the wording and year on the TCC. Week 1 and Month 1 are the weekly and monthly labels for non-cumulative treatment.
- Compare this payday on its own. Do not expect unused earlier credits to appear in the calculation.
- Ask Revenue why the basis applies. Revenue directs employees to MyEnquiries for this question.
- Do not confuse it with Emergency Tax. Emergency rates arise when normal Revenue details are unavailable.
- Review the year if it remains in place. Revenue says to submit an Income Tax Return if you are still on Week 1 basis at year end.
Frequently asked questions
What does Week 1 mean on an Irish payslip?
It means PAYE and USC are calculated for that payday without accumulating pay, credits and bands from 1 January.
Is Month 1 the same as Week 1 basis?
Yes. Month 1 is the monthly-payroll label for the same non-cumulative treatment.
Is Week 1 basis the same as Emergency Tax?
No. Week 1 uses ordinary period credits and bands without looking back. Emergency basis applies when payroll cannot obtain normal Revenue instructions.
Why is my PAYE higher on Week 1 basis?
Earlier unused credits or rate band cannot help the current payday. The difference is most noticeable after unpaid periods or variable pay.
Can payroll refund tax while I am on Week 1 basis?
Revenue says the employer cannot make the backdated Income Tax or USC refund until a cumulative certificate/RPN is issued.
How do I get changed to cumulative basis?
Ask Revenue through MyEnquiries why the current basis applies and provide any information requested. The employer must follow the latest RPN.
What if I am still on Week 1 basis at year end?
Revenue advises submitting an Income Tax Return in PAYE Services so the final annual position can be reviewed.
Can a PAYE calculator reproduce Week 1 payroll?
A calculator can provide a normal annual comparison, but the exact result depends on the RPN, pay history and period rounding used by payroll.
Sources & references
Related calculators
Use these tools for the numbers behind this guide.