How to read your code
- Multiply the number by 10. 1257 means £12,570 of tax free income.
- Read the letter. L is the standard allowance, M and N relate to the marriage allowance, and BR, D0 or D1 tax all income at a set rate.
- Watch for K codes. A K code adds tax because deductions exceed your allowance, often due to benefits or untaxed income.
- Spot emergency codes. W1 or M1 tax each period in isolation until HMRC issues the right code.
How to check and correct it
Check your code in your Personal Tax Account or the HMRC app, where you can see how it was worked out. If it looks wrong, for example because a benefit has ended or you changed jobs, HMRC can reissue it, and you can reclaim overpaid tax or settle any shortfall.
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Frequently asked questions
What does my tax code mean?
The number times 10 is your tax free allowance, so 1257L means £12,570 tax free. The letter carries meaning, such as L for the standard allowance or K for a code that adds tax.
How do I check my tax code?
Look in your Personal Tax Account or the HMRC app, where you can see the code and how it was worked out. Compare it to your income and any benefits.
What is a K tax code?
A K code means deductions such as benefits or untaxed income exceed your allowance, so tax is added to your pay rather than allowance being given.
Why is my tax code wrong?
Common reasons are changing jobs, a benefit starting or ending, having more than one income, or HMRC collecting an old underpayment through your code.
How do I correct a wrong tax code?
Contact HMRC or ask your accountant. HMRC can reissue the code, and you can reclaim overpaid tax or arrange to pay any shortfall.