What does my tax code mean and how do I check if it is right?

Full answer

Your tax code tells your employer or pension provider how much tax-free income you are entitled to before PAYE deductions begin, and checking it periodically is one of the simplest ways to catch payroll errors early. **Reading the standard code: 1257L** The number 1257 represents £12,570 of tax-free Personal Allowance (multiply by 10 to get the full figure) -- this is the standard allowance for most people in 2026/27 who have no employment benefits, additional income, or other adjustments affecting their allowance. The letter L simply confirms you are entitled to the standard Personal Allowance. **Common letter suffixes** M means you have received a Marriage Allowance transfer from your partner (10% boost to your allowance); N means you have transferred 10% of your allowance to your partner; T is used where HMRC needs to review your code and other factors are involved; 0T means you have no Personal Allowance at all, often used for very high earners whose allowance has been fully tapered away, or when starting a job with incomplete information. **K codes -- negative allowance** A K code (e.g., K475) means your untaxed income or deductions (such as company car benefits or previous underpaid tax being collected) exceed your Personal Allowance, so instead of tax-free income, an ADDITIONAL amount is added to your taxable income before tax is calculated -- this is normal for people with substantial benefits in kind but should still be checked for accuracy. **BR, D0, D1 codes** BR means all income is taxed at the basic rate (20%) with no Personal Allowance applied, commonly used for a second job or pension where your allowance is already fully used against your main income; D0 taxes everything at higher rate (40%); D1 taxes everything at additional rate (45%) -- these are common for secondary income sources. **W1/M1 -- emergency, non-cumulative codes** A code ending in W1 (Week 1) or M1 (Month 1) means tax is calculated on a non-cumulative, pay-period-only basis rather than accounting for the whole year's allowance progressively -- this is typically temporary while HMRC gathers full information, and usually self-corrects once a cumulative code is issued. **How to check if yours is right** Log into your Personal Tax Account on gov.uk to see your current tax code and the reasoning behind it (including any adjustments for benefits, previous under/overpayments, or other income) -- compare this against your actual circumstances, and if something looks wrong (for example, a K code when you have no benefits, or a 0T code when you should have your full allowance), contact HMRC to query it. **Practical tip** Check your tax code every time your circumstances change significantly -- new job, new benefits, marriage allowance claims, or a change in additional income -- since an outdated code can persist for months, either overcharging or undercharging you until it is corrected.

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