How to Check If HMRC Owes You a Tax Refund

Millions of people overpay tax each year without realising it — often through an incorrect PAYE tax code, a stopped job partway through the tax year, or unclaimed work expenses. With HMRC currently focused on the 31 July Payments on Account deadline for Self Assessment customers, it's a good moment to check whether you're due money back rather than owing more.

Common reasons you might be owed a refund

• Wrong tax code: if you changed jobs, had multiple employers, or came off Marriage Allowance without HMRC updating your code, you may have paid too much via PAYE. Check your code against GOV.UK's tax code checker.
• Emergency tax on a new job: new starters are sometimes taxed on an emergency code until HMRC receives full details, which can overtax the first few payslips.
• Unclaimed employment expenses: uniforms, tools, professional subscriptions and working-from-home costs can qualify for tax relief on employment expenses.
• Overpaid Payments on Account: if your income dropped and you paid Self Assessment payments on account based on last year's higher earnings, you may be due a repayment once your return is filed.
• Pension contribution relief not automatically claimed: higher-rate taxpayers in relief-at-source pension schemes often need to actively claim the extra relief via Self Assessment.

New for this year: Child Benefit prepopulation

From mid-July 2026, around 300,000 Self Assessment customers will have their (or their partner's) Child Benefit information pre-populated on their online return, aimed at reducing errors in the High Income Child Benefit Charge calculation — a common source of both underpayment and overpayment in the past.

Checklist: how to check and claim

• Log into your Personal Tax Account and review your current tax code and estimated income for the year.
• Compare your tax code to your actual circumstances — job changes, marriage allowance transfers, and benefits-in-kind are the most common triggers for errors.
• If you file Self Assessment, check whether your Payments on Account were based on outdated income figures before the 31 July deadline.
• Gather receipts for any unclaimed employment expenses (uniforms, subscriptions, working-from-home) going back up to four tax years.
• Submit a claim via the P87 form (employees not in Self Assessment) or include the relief directly on your Self Assessment return.
• If you believe you've overpaid via PAYE in a previous tax year, you can claim a refund for up to four years back.
• Watch for a P800 letter from HMRC — but don't wait for one, as not everyone owed a refund receives a proactive notice.

Beware refund scams

HMRC never sends emails or texts asking you to click a link to "claim a refund." Report suspicious messages to [email protected] and only ever check refund status via your official Personal Tax Account.

Key Numbers

• Payments on Account deadline: 31 July 2026
• Backdated expense claims allowed: up to 4 tax years
• Child Benefit data prepopulation rollout: affects roughly 300,000 customers from mid-July 2026

Sources

• GOV.UK: taxpayers urged to get ahead of July Self Assessment payment deadline
• ICAEW: Tax news in brief, 1 July 2026
• GOV.UK: tax relief for employees
• GOV.UK: understand your Self Assessment bill
• GOV.UK: Personal Tax Account

Educational content only — not financial advice.