UK Tax Codes Explained: How to Read and Check Your PAYE Code
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Read the numbers and letters in a tax code, understand emergency codes and check unexpected changes with HMRC.
Your tax code tells payroll how to calculate Income Tax on a job or pension. It is not a direct instruction for National Insurance, pension contributions or student loan deductions. A code different from 1257L can be correct.
What does 1257L mean?
1257L is currently used for many people with one job or pension and the standard £12,570 Personal Allowance. The number broadly represents the tax-free amount divided by 10. L indicates entitlement to the standard allowance, although the number can be adjusted for your circumstances.
In England, Wales or Northern Ireland, a £30,000 salary with the full standard allowance leaves £17,430 subject to Income Tax. At 20%, that is £3,486 for the year before other adjustments. Scotland uses different employment tax bands.
Check HMRC's explanation of tax code numbers and letters.
Common codes and markers
| Code or marker | What it normally indicates |
|---|---|
| L | Entitlement to the standard Personal Allowance |
| BR | All pay from that source taxed at the basic rate |
| D0 or D1 | All pay from that source taxed at the higher or additional rate outside Scotland |
| 0T | No Personal Allowance at this source; tax bands still apply |
| M or N | A Marriage Allowance transfer received or made |
| S prefix | Scottish Income Tax treatment |
| C prefix | Welsh Income Tax treatment |
| NT | No Income Tax deducted from this source |
| W1, M1, X or NONCUM | Current-period calculation instead of cumulative tax |
Scottish codes such as SD0 and SD1 use different bands from D0 and D1. Check the full official explanation rather than applying the same rate to every regional code.
What does a K code mean?
A K code can apply when items deducted from your tax-free allowance exceed the allowance itself. Examples include taxable benefits, State Pension or tax owed from an earlier year. Payroll adds a coded amount to taxable income rather than subtracting an allowance.
It does not mean that the number in the code is a bill you must pay immediately. A K-code deduction is also subject to a limit of half the pre-tax pay or pension for the period. See HMRC's K-code guidance.
Emergency tax does not always mean extra tax
A code such as 1257L M1 can still give a monthly share of the standard allowance. It ignores earlier pay and tax in the year for that calculation. With steady pay and no earlier adjustment needed, the deduction can match a normal month. With a pay change, gap in work or earlier overpayment, the result may differ.
See the official emergency-code explanation.
Check your tax code
Start with the code used on your payslip and compare it with HMRC's current-year Income Tax record. Check the period the payslip covers, then work through the following steps.
- Check the information behind the code. Compare HMRC's estimated earnings, active jobs and pensions, benefits and earlier tax owed with your circumstances. Multiple jobs do not each receive a separate full Personal Allowance.
- Identify who needs to correct it. If payroll has the wrong pay details or has not applied the relevant HMRC instruction, ask the employer to investigate. If HMRC's income, employment or benefits record is wrong, update it through the official service.
- Provide missing starter details. Give a new employer your P45 when available. Before a first payment, a starter checklist can help if you have no P45. See the job-change guide for that process.
- Keep evidence. Retain payslips, your P45 or P60 and coding notices. A code change may produce a refund or collect tax owed, depending on the cumulative record.
- Check the next payment. Confirm which code was used and ask payroll or HMRC about a remaining difference. Do not assume a fixed refund amount or payment date before the record is checked.
HMRC says a tax-code update after starting a job can take up to 35 days. Follow the official emergency-code next steps if you started longer ago and the details still look wrong.
If you think you have paid too much
For the current year, a corrected cumulative code may return excess tax through payroll. After the year ends, the route can involve a P800 calculation, Self Assessment or a separate claim. P50 is for certain people who have stopped working, rather than a general refund form.
Use GOV.UK's refund checker to identify the appropriate route. It does not itself submit a refund claim. Read the Income Tax refund guide for a worked overpayment example and deadlines.
The salary calculator estimates deductions for its supported settings. It does not establish refund entitlement or reproduce your full cumulative PAYE record.