Had a summer job? You may have overpaid tax – here's how to check and claim a refund

Why you may have paid too much tax

In the current tax year (6 April 2025 to 5 April 2026), most people can earn up to £12,570 without paying any income tax – this is your tax-free personal allowance.

To work out how much income tax to deduct from your pay, your employer uses a tax code – a short string of letters and numbers, for example: 1257L. These codes are crucial.

When you start a new job, you can give your employer one of the following to help ensure you're put on the correct tax code:

• A P45, which you should have been given by your previous employer after you stopped working; or

• A starter checklist, a form that you complete to tell your employer about your circumstances.

If you didn't provide either of these, or your employer simply made a mistake or couldn't process the info on time, you'll likely be on a temporary emergency tax code instead – such as 1257L W1, 1257L M1 or 1257L X.

With these emergency codes, tax is calculated just on that week's or month's pay in isolation, so you don't get the full benefit of your yearly tax-free personal allowance. For example, if you stopped working after only a few weeks or months, you may have earned well below £12,570 but still been taxed – in which case you could be due a refund.

Note on National Insurance (NI): While this also comes out of your pay, it's separate and works differently. If you're an employee, NI is worked out each payday on what you earn in that pay period only, without taking into account your earnings for the rest of the tax year. You pay NI when your earnings are above the main threshold of £242 a week or £1,048 a month. There's no annual threshold or allowance like there is with Income Tax – so you won't get NI back just because you stop working part-way through the year.

How to check and claim a refund

Here's what to do:

• If this was your only paid employment since 6 April 2025 and you won't work again this tax year. If you've finished the job (and you won't work again between now and 5 April 2026), you can claim a refund online. It may take a couple of weeks to get a reply, but the refund will then be paid directly into your bank account.

• If you're still working, or you may work again this tax year. Here there are a couple of steps...

  • Check your tax code & contact HM Revenue & Customs (HMRC) to correct it if wrong. You can find this on your payslips or through your Gov.uk personal tax account. If your tax code ends in W1, M1 or X, you are (or were) on an emergency code. If so, call HMRC on 0300 200 3300 to resolve it.

  • You'll get a new tax code to help you reclaim any overpaid tax. If you're still working (or have/will start a different job this tax year), HMRC will update your tax code and your (new) employer will use that to automatically adjust your pay to refund any overpaid tax.

For more help with income tax, see our Tax code calculator and guide.