Getting a refund of a Self Assessment credit

Q: How do I ask HMRC to repay a credit?

The routes depend on how you deal with HMRC: Self Assessment online account: sign in, check the balance and choose "Request a repayment", then follow the steps. Personal tax account or business tax account: choose "Claim a tax refund". Without an online account: you can set one up, or contact HMRC. SAM110001 lists written requests and telephone requests as accepted routes, with identity checks for calls. Through an agent: an authorised agent can make the request, and the refund can be paid to them if you nominate them in writing. See nominating repayments to an agent. HMRC only pays refunds into UK bank accounts. If you have no account, GOV.UK says you can nominate someone else to receive the money. HMRC does not send details of refunds by email, so treat any email offering a tax refund as suspicious.

Q: What can delay or reduce the repayment?

Several things can hold a refund back or shrink it: Security and risk checks. Every draft repayment is screened. GOV.UK says checks can add up to 12 more weeks, and you should contact HMRC if nothing has arrived after 14 weeks in total. The background is covered in why HMRC holds a Self Assessment repayment. Recent payments. SAM110140 sets a 14 day inhibition period from receipt of a payment before it can be repaid, so a credit created by last week's payment will wait. An open enquiry. Section 59B(4A) says a repayment need not be made until an enquiry into the return is completed, although the officer may make a provisional repayment. Other debts. HMRC can use a credit to pay a different tax debt you owe. See HMRC set off of repayments. Flags on the record. SAM110205 lists signals that stop automatic repayment, including insolvency, death with no personal representative recorded, an address marked as returned letter, and uncleared payments.

Q: What does this look like in practice?

Illustration only. Sam paid payments on account of £3,000 on 31 January and £3,000 on 31 July for the year. In December Sam files the return online, showing tax of £4,500 for that year. That makes £1,500 overpaid, and the first payment on account for the next year, half of £4,500, is £2,250 due on 31 January. Because that charge falls due within 45 days, HMRC uses the £1,500 against it rather than paying it out, and Sam pays the remaining £750 on 31 January. If Sam had filed in May instead, the 31 January charge would be months away. Sam could tick the repayment box, receive £1,500 within a few weeks, and budget to pay the full £2,250 in January. Either way the same money changes hands; only the timing differs.

Q: What mistakes do people make?

Assuming the credit is lost. It stays on the record until used or claimed. If HMRC cannot repay it, for example on a closed record, SAM110180 says it is transferred to HMRC's central accounting system with instructions for dealing with it. Requesting twice. A second request while the first is being processed can delay payment. Forgetting the 45 day rule and expecting a refund in December when a January payment is about to fall due. Not asking after an amendment. SAM110020 says automatic repayment is not appropriate where the credit arises from an amended return, so check the account and request it. Confusing a credit with an overpayment claim for a closed year. If the tax itself was wrong and the amendment window has passed, you need an overpayment relief claim, which has a four year time limit. If HMRC opens a check into your return, tax investigation insurance pays your accountant's fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.

A credit on your Self Assessment account means HMRC holds more of your money than your charges to date. HMRC keeps it on the account until a charge falls due or you ask for it back, and it will not repay any part needed for tax due within the next 45 days. To get the rest, choose “Request a repayment” in your online account or write to HMRC; refunds usually arrive within two weeks, though security checks can add up to 12 weeks.

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Why is there a credit on my Self Assessment account?

Your Self Assessment statement is a running account. Charges go on it (balancing payments, payments on account, penalties, interest) and so do payments and other credits. A credit is simply the amount by which payments and credits exceed charges that are already due. The common causes are:

Payments on account were too high. Section 59B of the Taxes Management Act 1970 compares the tax in your self assessment with your payments on account and tax deducted at source. If the payments exceed the liability, the difference is repayable to you.
You reduced your payments on account after paying them, for example with a claim on form SA303 under section 59A. HMRC’s Self Assessment Manual at SAM110001 lists these claims as a source of repayments.
You paid twice or paid too much, or paid into the wrong reference. Payments made in error are another listed source.
You amended your return or claimed relief that reduced an earlier year’s tax, such as a loss or pension contribution carried back.
A Budget Payment Plan overshot. GOV.UK says that if your regular Direct Debits come to more than the next bill, you are in credit and can ask for a refund.
The business or source has stopped, for example after death, emigration or ceasing to trade.

Will HMRC pay it back automatically?

Not unless you have asked. SAM110001 says a credit balance “will be held until either a charge becomes due or a repayment is requested”, and that a repayment will not be made unless the customer or agent makes a specific request. The usual place to ask is the repayment box on the tax return itself. A request on the return covers any later repayment for that year too, for example after an amendment.

Where you did ask on the return, HMRC’s guidance says the refund will usually be paid within two weeks of filing online, or of the date on the SA302 calculation for a paper return, into the account you gave. If you paid by card, HMRC will try to refund to that card first. If you have a submission reference for your request, do not ask again, as a second request can cause delay.

Where there was no request, the credit simply sits on the account. SAM110180 confirms that an unclaimed credit remains on the record until a repayment is claimed or a liability falls due and the credit can be used against it.

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When should I leave the credit against the next bill?

Leaving the money where it is often makes sense when a payment is coming up soon. Under SAM110020, when HMRC works out how much it can repay, it reduces the amount by anything “becoming due” within 45 days, such as a balancing payment or a first payment on account. GOV.UK puts it simply: you may not get a refund if you have tax due in the next 45 days, and the money will be deducted from the tax you owe instead.

Leaving the credit in place is sensible where:

your next payment on account is due within a few weeks and the credit would only be paid out and then paid back in;
you expect the current year’s bill to be higher and would rather pay it down now; or
the credit is small. HMRC’s system will not create an automatic repayment of less than £10, although SAM110020 says a smaller amount can still be repaid if you pursue the request.

Ask for the money back where the next charge is months away, where you need the cash, or where the credit came from a payment made by mistake. HMRC’s manual also says that if a credit has been earmarked for a charge within the 45 day window, you can still ask for that amount to be repaid, provided you ask before the charge’s due date.

How do I ask HMRC to repay a credit?

The routes depend on how you deal with HMRC:

Self Assessment online account: sign in, check the balance and choose “Request a repayment”, then follow the steps.
Personal tax account or business tax account: choose “Claim a tax refund”.
Without an online account: you can set one up, or contact HMRC. SAM110001 lists written requests and telephone requests as accepted routes, with identity checks for calls.
Through an agent: an authorised agent can make the request, and the refund can be paid to them if you nominate them in writing. See nominating repayments to an agent.

HMRC only pays refunds into UK bank accounts. If you have no account, GOV.UK says you can nominate someone else to receive the money. HMRC does not send details of refunds by email, so treat any email offering a tax refund as suspicious.

What can delay or reduce the repayment?

Several things can hold a refund back or shrink it:

Security and risk checks. Every draft repayment is screened. GOV.UK says checks can add up to 12 more weeks, and you should contact HMRC if nothing has arrived after 14 weeks in total. The background is covered in why HMRC holds a Self Assessment repayment.
Recent payments. SAM110140 sets a 14 day inhibition period from receipt of a payment before it can be repaid, so a credit created by last week’s payment will wait.
An open enquiry. Section 59B(4A) says a repayment need not be made until an enquiry into the return is completed, although the officer may make a provisional repayment.
Other debts. HMRC can use a credit to pay a different tax debt you owe. See HMRC set off of repayments.
Flags on the record. SAM110205 lists signals that stop automatic repayment, including insolvency, death with no personal representative recorded, an address marked as returned letter, and uncleared payments.

Does HMRC pay interest on the credit?

Sometimes. A credit that represents tax you were overcharged can attract repayment interest, worked out by HMRC’s systems. SAM110260 notes, however, that an unallocated payment, one that was never set against a charge, does not generally attract it. A payment that was set against a charge which was later reduced does qualify. The rules on when interest starts and stops are on HMRC repayments and repayment interest.

What does this look like in practice?

Illustration only. Sam paid payments on account of £3,000 on 31 January and £3,000 on 31 July for the year. In December Sam files the return online, showing tax of £4,500 for that year. That makes £1,500 overpaid, and the first payment on account for the next year, half of £4,500, is £2,250 due on 31 January. Because that charge falls due within 45 days, HMRC uses the £1,500 against it rather than paying it out, and Sam pays the remaining £750 on 31 January.

If Sam had filed in May instead, the 31 January charge would be months away. Sam could tick the repayment box, receive £1,500 within a few weeks, and budget to pay the full £2,250 in January. Either way the same money changes hands; only the timing differs.

What mistakes do people make?

Assuming the credit is lost. It stays on the record until used or claimed. If HMRC cannot repay it, for example on a closed record, SAM110180 says it is transferred to HMRC’s central accounting system with instructions for dealing with it.
Requesting twice. A second request while the first is being processed can delay payment.
Forgetting the 45 day rule and expecting a refund in December when a January payment is about to fall due.
Not asking after an amendment. SAM110020 says automatic repayment is not appropriate where the credit arises from an amended return, so check the account and request it.
Confusing a credit with an overpayment claim for a closed year. If the tax itself was wrong and the amendment window has passed, you need an overpayment relief claim, which has a four year time limit.

If HMRC opens a check into your return, tax investigation insurance pays your accountant’s fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.