Tax Code Checker
Type the tax code from your payslip or P60 — the checker decodes the numbers and letters, shows your tax-free amount and flags codes that often mean overpaying.
How it works
The NUMBERS in your code are your tax-free allowance divided by 10: code 1257L means £12,570 a year tax-free — the standard personal allowance. A different number means HMRC has adjusted your allowance for benefits in kind, untaxed income or a marriage allowance transfer.
The LETTERS describe your situation: L standard · M received marriage allowance (+10%) · N transferred marriage allowance (−10%) · T HMRC needs to review · BR all income taxed at 20% · D0 all at 40% · D1 all at 45% · NT no tax · S Scottish rates · C Welsh rates.
K codes work in reverse: K497 means £4,970 is ADDED to your taxable income (untaxed income, e.g. a company car, exceeds your allowance). W1/M1/X suffixes mean an emergency code calculated per-payday without the year’s history — common after a job change, and a frequent cause of temporary overpaying.
FAQ
What does tax code 1257L mean?
It is the standard code for 2026/27: £12,570 of tax-free personal allowance spread across the year, with the L meaning no special circumstances. Most employees with one job and no taxable benefits should be on 1257L. If your code differs and you don’t know why, check your HMRC personal tax account — the numbers reveal exactly what HMRC has added or removed.
Why am I on an emergency tax code (W1, M1 or X)?
Emergency codes appear when your employer doesn’t yet have your full tax history — typically after starting a new job without a P45, starting a first job, or getting company benefits. Each payday is taxed in isolation, so you can overpay if your income varies. The fix is usually automatic once HMRC processes your details, and any overpaid tax comes back through your pay or a refund.
What is a K tax code?
A K code means your untaxed income (company car, state pension alongside a job, tax owed from earlier years) exceeds your personal allowance, so instead of getting tax-free pay, an amount is ADDED to your taxable income. K497 adds £4,970 a year. A safety rule caps the deduction: no more than half of your gross pay in any period can be taken through a K code.
How do I fix a wrong tax code?
You cannot change it through your employer — the code comes from HMRC. Sign in to your personal tax account at gov.uk (or call HMRC on 0300 200 3300) and update your income, benefits or jobs; a corrected code is sent to your employer automatically. Refunds for the current year arrive through your next payslips; earlier years are refunded separately, and you can claim back up to 4 tax years.