Tax code
checker
HMRC issues millions of wrong tax codes every year. They never write to apologise. They definitely won’t write to refund you. Check your code in seconds.
Spots emergency codes
Flags BR, 0T, W1/M1/X markers that often mean you’re overpaying tax.
All UK code types
1257L, K-codes, D0/D1, NT, M/N (Marriage Allowance), S (Scotland) and C (Wales).
Claim back 4 years
If your code was wrong, you can reclaim overpaid tax for the current year + 4 previous.
Tax code checker
Decode your tax code, spot emergency codes, and find out if you might be owed a refund.
Tax codes are 3–4 numbers + a letter, or a letter prefix (BR, D0, K, etc.).
Common UK tax codes
Common questions
What does 1257L mean?
1257L is the standard UK tax code for 2026/27. The 1257 means £12,570 of tax-free personal allowance, and the L suffix means you get the standard allowance with no adjustments. Most employees with a single job and no benefits-in-kind have this code.
Why am I on a BR tax code?
BR (Basic Rate) means everything you earn under that employment is taxed at 20% with no personal allowance. It’s used for second jobs or pensions, on the assumption your £12,570 PA is being used by your main job. If BR is your ONLY job, you’re overpaying — call HMRC and they’ll fix it.
What's an emergency tax code?
Codes ending W1, M1 or X are emergency (non-cumulative) codes — typically issued when you start a new job without a P45. Tax is calculated on each pay period in isolation rather than cumulatively, which often means you overpay until HMRC has the full picture. You usually get the difference back automatically at year-end.
How far back can I claim a tax refund?
You can reclaim overpaid tax for the current tax year and the previous 4 tax years. From April 2026 that means anything from 2021/22 onwards. Use your HMRC personal tax account or send an R38 form. Anyone offering to do it for you for a fee is doing something you can do yourself in 5 minutes.
What's a K tax code?
K codes mean your deductions (e.g. company car, medical insurance, owed tax from a previous year) exceed your personal allowance, so you have a *negative* tax-free amount. K500 means £5,000 is added to your taxable income before tax is calculated — common for company-car drivers.
HMRC ignoring your refund claim?
If your code is wrong and HMRC won’t fix it — or your refund has been “processing” for 8 weeks — we’ll help you escalate properly.
Start your free complaint