Your tax code tells your employer how much Income Tax to deduct from your pay. Getting it wrong means paying too much or too little tax.
What the numbers mean
The number in your tax code represents your tax-free allowance divided by 10. The standard personal allowance (2024/25) is £12,570, so the standard code is 1257L.
Common letters
- L: you're entitled to the standard personal allowance
- M or N: you're sharing part of the Marriage Allowance
- BR: all income from this source is taxed at basic rate (often used for second jobs)
- K: you have untaxed income larger than your allowance
Checking your code
Check your payslip, P60 or P45. If it looks wrong, contact HMRC directly through your personal tax account at gov.uk.