How to check your tax code is right (UK)

Your tax code tells your employer how much tax to take from your pay, and a wrong one means you pay too much or too little until it is corrected. For the 2026 to 2027 tax year, which runs from 6 April 2026 to 5 April 2027, the standard code for most people with one job is 1257L, which reflects a tax-free Personal Allowance of £12,570. To check yours, find the code on a payslip and compare it with what HMRC holds.

How do I check my tax code?

Look at your most recent payslip or your P45 or P60, where the code is printed, then check it against HMRC. gov.uk has a page for checking your Income Tax, where you can see your tax code, your estimated tax for the year and what it is based on, and a guide to tax codes explains what each letter means.

See checking your Income Tax and tax codes. If the code differs from what you expect, HMRC can correct it and your employer then adjusts your pay.

What does my tax code mean?

The number is your tax-free allowance divided by ten, and the letter explains your situation. L means you get the standard Personal Allowance. M or N means you have given or received part of the Marriage Allowance. T means other calculations apply.

BR taxes all of your income from that source at the basic rate, D0 taxes it at the higher rate, and 0T gives you no allowance. A code that ends in W1 or M1 or X is an emergency code, which means HMRC is waiting for information.

What are the signs of a wrong tax code?

The common signs are a payslip that suddenly shows less take-home pay with no explanation, a code that starts with K or 0T when you have only one job, an emergency code that has lasted for months, and a code that does not match the allowance you expect.

A change of job, a company car, an unpaid tax bill being collected through your pay, or a second income can all change a code legitimately, so check why before assuming it is wrong.

How can Era help me check my tax code?

Upload your payslips and P60 to Era's document library, which reads and files them. Then ask Claude, ChatGPT or Gemini what tax code you are on according to your last three payslips, and whether the tax taken from your pay matches it. The assistant answers from your documents and points to the page it used.

Because the memory is shared, you can ask the same question in another assistant later.

If a code looks wrong, contact HMRC through the route that gov.uk describes, and keep the payslip pages as evidence. Our page on what a P60 is explains the end-of-year figures, and the pricing page shows what each Era plan includes.