UK PAYE explained · 2026/27 tax year

Cumulative vs non-cumulative PAYE: what is the difference?

Cumulative PAYE uses what you have earned and paid in tax so far this tax year. Non-cumulative PAYE works out tax using only the current pay period.

How cumulative PAYE works

On a cumulative code, payroll looks at your taxable pay and Income Tax paid from 6 April up to your current payday. It also gives you the proportion of your tax-free allowance and tax bands built up so far in the year. The calculation compares the tax due to date with tax already deducted and takes the difference this period.

That is why a later payslip can include a tax refund or a higher deduction: it may be catching up after earlier payroll information changed.

How non-cumulative PAYE works

On a non-cumulative code, payroll treats each weekly or monthly payment independently. It applies only that period's allowance and tax bands, without considering earlier taxable pay or Income Tax from the same tax year.

You may see this shown as M1 for monthly pay, W1 for weekly pay, X, or NONCUM. It is commonly called an emergency-tax basis.

Why you might be put on a non-cumulative basis

• You recently started a job and your employer does not have your P45 or previous pay details.
• HMRC is reviewing your tax position or issuing a temporary code.
• Your pay dates or employment information have changed and payroll needs to apply a code without earlier figures.

Which one is better?

Neither is automatically better. Cumulative PAYE is normally more accurate across the whole tax year because it can correct earlier differences. Non-cumulative PAYE can be appropriate temporarily, but it may not reflect tax already paid in a previous job or earlier period.

How to check your payslip

1. Look at the code shown by your employer. A suffix such as M1, W1, X or NONCUM indicates non-cumulative treatment.
2. If your payslip is cumulative, copy the taxable pay and Income Tax paid to date from the previous payslip into the NetPay Lens payslip checker.
3. If your code is non-cumulative, select non-cumulative PAYE in the payslip checker and check whether you recently changed jobs or provided a P45.
4. Check your current code in your HMRC Personal Tax Account if it does not reflect your circumstances.

Example: why the result can change

Imagine a person starts a new job in July without a P45. Their employer may initially use a month 1 code, so July tax is calculated as a standalone month. Once HMRC supplies the correct cumulative code and earlier pay details, a later payslip may adjust the tax to reflect the whole year to date.

Use the relevant tool