How do I claim back an overpaid Self Assessment payment on account?

Full answer

Overpaying payments on account is common when income falls during the year but the payments were based on a higher prior-year liability and were not reduced in advance -- fortunately, reclaiming the excess is usually straightforward once your return is filed. **Step one: file your return** The overpayment only becomes visible to HMRC once you submit your Self Assessment return for the relevant tax year, showing your actual final liability. HMRC's system automatically compares this to the payments on account you already made and calculates any surplus. **Step two: check your Self Assessment account** Log into your Government Gateway account and view your Self Assessment statement -- an overpayment will show as a credit balance. You can typically request repayment directly through the online account (there is usually a "request a repayment" option), and HMRC pays it by BACS transfer to your nominated bank account, usually within a matter of days to a couple of weeks. **Option to leave it as a credit instead** Rather than requesting a cash repayment, you can choose to leave the overpayment sitting on your account as a credit, which is then automatically used to reduce your next payment on account or balancing payment due. This can be convenient if you expect to owe further tax soon and want to avoid the admin of a repayment followed shortly by a new payment. **Repayment interest** If HMRC takes an unusually long time to process a repayment, or in certain circumstances where tax was clearly overpaid for an extended period, HMRC may pay a small amount of repayment interest, calculated at HMRC's official repayment interest rate -- though this is typically only relevant for longer delays or larger sums, not routine same-year overpayments processed promptly. **Worked example** Oliver made two payments on account of £3,000 each (£6,000 total) for 2025/26, based on his higher 2024/25 income. His actual 2025/26 self-employed profits fell, and his final tax bill for that year comes to £4,200. When he files his return, HMRC's system shows a £1,800 overpayment. Oliver logs into his personal tax account and requests the £1,800 be repaid to his bank account, receiving it within about two weeks -- alternatively he could have left it as a credit against his first 2026/27 payment on account, due the following January. **Watch out for repayment scams** HMRC does not text or email links asking you to "claim your refund" by entering bank details on an external site -- always access repayments through your official Government Gateway login, not via links in unsolicited messages, which are a common phishing tactic around Self Assessment deadlines. **Practical tip** If you know in advance your income has fallen, it is usually better to apply to REDUCE your payments on account before the deadline (avoiding the overpayment in the first place) rather than overpaying and then reclaiming afterwards, since this keeps more cash in your business or personal account throughout the year.

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