Tax Code Checker

Your tax code tells your employer how much tax-free income you are entitled to in the current tax year. If it's wrong, you are either paying too much tax or building up a tax debt that HMRC will eventually ask you to repay.

Millions of UK workers are on the wrong tax code every year. The most common mistakes happen when you change jobs, have more than one source of income, or receive taxable company benefits (like a company car or health insurance).

What if my tax code is wrong?

Your employer cannot change your tax code just because you ask them to — they must receive an official coding notice from HMRC.

To fix it, you need to contact HMRC directly. The easiest way is to log into your Personal Tax Account on gov.uk. You can view how HMRC has calculated your code and update your estimated income. Alternatively, you can call HMRC on 0300 200 3300 (have your National Insurance number ready).

Want to see how your tax code affects your take-home pay?

Use our real-time calculator to see exactly how much tax and National Insurance will be deducted from your next payslip.