How to Check If You've Overpaid Tax (and Get a Refund)

HMRC estimates that millions of UK workers overpay tax each year, often without realising. Here's how to check if you're one of them.

Common Reasons for Overpaying Tax

Wrong tax code

This is the #1 reason. If your tax code is wrong — perhaps after changing jobs, or because HMRC has outdated information — you could be paying too much every month. Check your code on your payslip and compare it to what you'd expect.

Emergency tax when starting a new job

If you started a new job without giving your employer a P45, you'll be put on emergency tax (usually a W1/M1 code). This often means overpaying for the first few months.

Leaving a job mid-year

If you were made redundant or left a job partway through the tax year, you may have overpaid. PAYE spreads your allowance across 12 months — if you only worked 8, you haven't used your full allowance.

Unclaimed expenses

If you pay for things required for your job — professional subscriptions, uniforms, tools, or working from home — you may be entitled to tax relief you're not claiming.

How to Check

1. Use our salary calculator to see what your annual tax should be
2. Compare this to the tax shown on your latest payslip (year-to-date figures)
3. Check your tax code matches 1257L (or your expected code)
4. Log into your HMRC personal tax account to review your records

How to Claim a Refund

If you've left a job: fill in form P50 (or P85 if leaving the UK). For a wrong tax code: call HMRC on 0300 200 3300 or update via your online account. For unclaimed expenses: file through Self Assessment or use the HMRC online tool. Refunds can be backdated up to 4 years.