Self-Assessment Tax Refunds: How to Claim Money Back from HMRC

A self-assessment tax refund is the money HMRC repays when you have paid more income tax than you actually owed for the tax year. If you are self-employed and your payments on account, deducted tax or expenses claims mean you have overpaid, you can reclaim the difference through your self-assessment tax return. This self-assessment tax return guide for the UK in 2026 explains who is owed a refund, how to claim it, and how quickly HMRC pays. Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice, helps self-employed people recover tax they should never have paid in the first place. Overpaid tax is common among sole traders, particularly those who pay tax in advance through payments on account, so it is always worth checking your position carefully.

Key Takeaways

• A self-assessment tax refund arises when the tax you have paid for a year exceeds your actual liability shown on your tax return.
• Payments on account are the most common cause of overpayment for the self-employed, as they are based on the previous year's profit.
• You claim a refund by completing your self-assessment tax return; HMRC calculates the overpayment automatically once the return is submitted.
• HMRC usually issues self-assessment refunds within 5 to 10 working days of the return being processed, paid directly to your bank account.
• You can claim a tax refund for up to 4 years after the end of the relevant tax year, so the deadline for 2022/23 is 5 April 2027.
• Claiming all allowable expenses on your self-employed tax return increases any refund due and reduces future tax bills.

Who is owed a self-assessment tax refund?

You are owed a self-assessment tax refund whenever the tax you have already paid for a year is greater than the tax your return shows you owe. For the self-employed, this happens most often through payments on account, which are advance instalments towards your bill based on the prior year's profit. If your profit falls, those instalments can exceed your actual liability and leave you in credit.

Refunds also arise when too much tax was deducted at source, for example through the Construction Industry Scheme (CIS) for subcontractors, or when you forgot to claim allowable expenses or pension contributions. CIS subcontractors frequently have 20% deducted from payments and find, after claiming expenses, that they have overpaid. Checking each of these areas on your self-employed tax return is the surest way to recover money.

How do you claim money back from HMRC?

You claim money back from HMRC by completing and submitting your self-assessment tax return, after which HMRC automatically calculates whether you have overpaid. There is no separate refund form for amounts within self-assessment; the figure is worked out from the income, tax paid and expenses you report.

Once your return is processed and shows a credit, you can request repayment through your HMRC online account, nominating the bank account you want the money paid into. For the most reliable and fastest payment, file online and provide your bank details rather than waiting for a cheque. A complete self-assessment with HMRC, listing every allowable expense and any tax already deducted, ensures the refund calculated is the full amount you are due. For the full process of completing your return, see our guide to self-assessment tax returns.

How long does a self-assessment refund take?

A self-assessment refund usually reaches your bank account within 5 to 10 working days of HMRC processing your return, though it can take longer if security checks are required. Online returns are processed faster than paper ones, and a refund requested with valid bank details is quicker than a repayment issued by cheque.

HMRC sometimes holds refunds for additional verification, particularly on first claims or larger amounts, which can extend the wait to a few weeks. Filing early in the tax year, rather than close to the 31 January deadline when HMRC is busiest, often results in a faster repayment. You can track the status of your repayment through your HMRC online account at any time.

A worked example for 2026/27

Consider Tom, a self-employed graphic designer. For 2025/26 he made profits of £45,000, giving income tax of £6,486 and Class 4 National Insurance of £1,946, a liability of £8,432. Based on that year, HMRC required payments on account of £4,216 each towards 2026/27, totalling £8,432.

In 2026/27 Tom's profit falls to £30,000, giving an actual income tax and Class 4 National Insurance liability of £4,532. Because he had already paid £8,432 on account, Tom has overpaid by £3,900. When he files his 2026/27 self-assessment tax return, HMRC calculates the overpayment and, once Tom requests repayment with his bank details, refunds the £3,900 directly to him. Had Tom claimed an additional £1,000 of allowable expenses he initially overlooked, his refund would have been larger still.

Note that from 6 April 2026, Making Tax Digital for Income Tax applies to sole traders and landlords with qualifying income above £50,000, who must keep digital records and submit quarterly updates plus a final declaration by 31 January. Tom is below this threshold for now, but those above £50,000 should keep digital records that make overpayments easier to spot and reclaim.

Frequently Asked Questions

How do I know if HMRC owes me a tax refund?

HMRC owes you a tax refund if the tax you have paid for a year exceeds the liability shown on your self-assessment tax return. The most common causes for the self-employed are payments on account based on a higher previous year, tax deducted under the Construction Industry Scheme, or unclaimed expenses. Your HMRC online account will show a credit once your return is processed.

Can I claim a tax refund from previous years?

Yes, you can claim a self-assessment tax refund for up to 4 years after the end of the relevant tax year. For example, a refund for the 2022/23 tax year must be claimed by 5 April 2027. If you missed allowable expenses or overpaid through payments on account in an earlier year, you can amend the return or write to HMRC within that window.

How long does HMRC take to pay a self-assessment refund?

HMRC usually pays a self-assessment refund within 5 to 10 working days of processing your return, paid directly to your nominated bank account. Refunds can take longer if HMRC carries out security checks, which is more likely on first claims or larger amounts. Filing online and early in the tax year generally results in faster repayment.

Will claiming expenses increase my tax refund?

Yes, claiming all allowable business expenses reduces your taxable profit, which lowers your tax bill and can increase any refund due. Common allowable expenses for the self-employed include use of home as office, travel, equipment, professional fees and software. Keeping accurate records throughout the year ensures you claim everything you are entitled to on your self-employed tax return.

How Blue Tick Can Help

Blue Tick Accountants reviews self-employed tax returns to make sure every allowable expense is claimed and every overpayment is recovered, so you receive the full refund HMRC owes you. The practice also helps clients manage payments on account and prepare for Making Tax Digital, reducing the risk of overpaying in future years. Head to our website and book a meeting now.

Conclusion

Many self-employed people are owed a tax refund without realising it, usually because payments on account or deductions at source exceeded their actual liability. Completing an accurate self-assessment tax return, claiming every allowable expense and providing your bank details is all it takes to reclaim the money, typically within 5 to 10 working days. Check your position each year so overpaid tax is returned to you rather than sitting with HMRC.

About the Author

This guide was written by Leon, founder of Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice that helps the self-employed, landlords and limited company owners across the UK manage their tax efficiently. It was last reviewed for the 2026/27 tax year.

This article is intended for general informational purposes only and does not constitute tax, legal, or financial advice. Tax rules are subject to change and their application will depend on your individual circumstances. You should always seek advice from a qualified professional before taking action. Blue Tick Accountants accepts no liability for decisions made on the basis of this content.

Related reading: Self-Assessment for Beginners: Everything You Need Before You Start.