How do I claim back tax if I am in self assessment?

Updated on 10 November 2016

If you are in self assessment and you overpay tax, you do not need to submit a separate claim for repayment. You claim your tax repayment through your self assessment tax return. We explain how.

How do tax repayments through self assessment generally work?

If you overpay tax on your income and you complete a self assessment tax return, HM Revenue & Customs (HMRC) will deal with your repayment once they have processed your tax return.

You can state in the tax return how you would like the repayment to be paid to you. You can have it:

  • paid directly into your bank account,
  • paid to you by cheque, or
  • deducted from your next self assessment tax liability, for example, against the next tax year’s ‘payment on account’ if you are due to make one.

Alternatively, if you owe HMRC another amount, for example, a tax credits overpayment, you might ask them to ‘offset’ the repayment against that amount. This means they will take the amount you are due to be repaid off the other amount you owe. They will then repay any remaining repayment or you will have to pay the rest if you still owe some.

You complete your tax return after the end of the tax year. The sooner you submit your tax return, the sooner you will receive your repayment, or offset. If you submit your tax return online rather than on paper, it might be dealt with sooner and you will get your repayment faster.

HMRC sometimes also want to check some things before sending your repayment, as part of their aims to prevent people claiming tax back fraudulently. If you have been waiting several weeks to hear back from HMRC about your refund, we suggest you telephone them to find out what is happening.

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How do I claim a refund if I made a mistake on my tax return?

Sometimes you may make a mistake on your tax return and pay too much tax.

In this situation, you need to amend or correct your tax return first. Once HMRC have processed the amended tax return, they will send you any repayment due or offset it against other amounts that you owe.

There are time limits for correcting your tax return. The normal limit is 12 months from the 31 January after the end of the tax year. For example, the normal deadline for amending your 2015/16 tax return is 31 January 2018.

We provide more details on these time limits in our section on self assessment.

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How do I claim a refund if it is too late to amend my tax return?

If you made a mistake in your tax return, and paid too much tax, but only realise after the deadline for amending the tax return has passed, you may still be able to claim a repayment of overpaid tax.

In this situation you will need to write to HMRC and tell them about your mistake. You can write to HMRC using the postal address on the most recent correspondence you have from them, or you can use the contact details on HMRC’s website.

Your letter, should:

  • give your full personal details – your name, address, National Insurance number and unique taxpayer reference (UTR);
  • refer to the tax year to which the repayment relates;
  • include as much information as possible about why you think you have paid too much tax and the mistake you made;
  • enclose evidence of the tax that you have paid, including copies of P60s and P45s if you have them – keep the originals;
  • say how you would like to receive any repayment – you can have it paid directly into your bank account, paid by cheque, or deducted from your next self assessment tax liability;
  • be signed and dated in ink.

Keep a copy of your letter and any enclosures and ask the Post Office for a proof of posting in case of later query.

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What are the time limits for claiming back tax?

The time limits for claiming back overpaid tax are set out in the introduction page of this section.

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