HMRC Tax Code Decoder UK 2025/26 — What Does My Tax Code Mean?
Your tax code tells your employer how much income to tax you on before deducting tax. The most common code is 1257L — meaning you get the full personal allowance of £12,570. Use this decoder to understand exactly what your code means and whether it looks correct.
Standard tax code 2025/26: 1257L (personal allowance £12,570). Codes are issued by HMRC and applied by your employer. If you think your code is wrong, contact HMRC on 0300 200 3300 or via your Personal Tax Account at gov.uk.
Common Tax Code Suffixes Explained
| Letter(s) | Meaning |
|---|---|
| L | Standard personal allowance (most common — e.g. 1257L) |
| M | Marriage Allowance — you have received 10% of partner's allowance |
| N | Marriage Allowance — you have transferred 10% of your allowance to partner |
| T | HMRC needs to review your code (income over £100,000, or complex affairs) |
| BR | All income taxed at basic rate (20%) — no personal allowance on this job |
| D0 | All income taxed at higher rate (40%) — no personal allowance on this job |
| D1 | All income taxed at additional rate (45%) |
| NT | No tax — employer deducts nothing (e.g. some overseas arrangements) |
| K prefix | Negative allowance — you owe tax on unpaid tax from previous years or benefits in kind |
| S prefix | Scottish income tax rates apply |
| C prefix | Welsh income tax rates apply |
| W1 / M1 | Emergency code — tax calculated on a non-cumulative weekly or monthly basis |
Why Might My Tax Code Be Wrong?
Tax codes can be incorrect for many reasons: starting a new job and HMRC not having up-to-date information; changing from one employer to another; receiving benefits in kind (company car, private health insurance); having multiple jobs or pension income; HMRC applying an incorrect underpayment from a previous year; or receiving or stopping Marriage Allowance. Always check your P60, payslip, or Personal Tax Account to confirm your code is right.
How to Fix a Wrong Tax Code
Contact HMRC online via your Personal Tax Account, or by phone on 0300 200 3300. HMRC will issue a corrected code to your employer. If you have overpaid tax, HMRC will refund you either through your payroll (if in-year) or via a cheque or bank transfer after the tax year ends.