What Happens If You Overpay Tax UK — How to Claim a Refund

Millions of people overpay tax each year without realising. Here’s how to check and get your money back.

Common Reasons for Overpaying Tax

How to Check If You’ve Overpaid

Step 1 — Check Your Tax Code

Your tax code appears on your payslip and P60. For 2026/27, the standard code is 1257L, meaning a £12,570 personal allowance.

Common wrong codes:

Step 2 — Use Your Personal Tax Account

Sign in at gov.uk/personal-tax-account to:

• See your current tax code and what it’s based on
• Check if HMRC thinks you owe tax or are owed a refund
• View previous years’ tax summaries
• Update your details

Step 3 — Check Your P800

HMRC automatically checks whether you’ve paid the right tax after each tax year ends (April). If they find an overpayment, they send a P800 tax calculation — usually between June and October.

The P800 tells you:

• How much tax you should have paid
• How much you actually paid
• Whether you’re owed a refund (or owe more)

How to Claim a Refund

If You Get a P800

1. Log in to your Personal Tax Account
2. The refund should appear as claimable
3. Choose bank transfer (5 working days) or wait for a cheque (2-4 weeks)
4. If you don’t claim online within 45 days, HMRC sends a cheque automatically

If You Haven’t Received a P800

Contact HMRC directly:

• Online: Through your Personal Tax Account — use the messaging service
• Phone: 0300 200 3300 (Monday to Friday, 8am to 6pm)
• Post: Write to HMRC PAYE, PO Box 1970, Liverpool, L75 1WX

You’ll need your National Insurance number, P60, and details of what you think went wrong.

If You’re Self-Employed

Overpaid tax through Self Assessment is automatically refunded or offset against future payments. You can:

• Request a refund through your online Self Assessment account
• Wait for HMRC to process it after filing your return

Claiming for Previous Years

You can claim overpaid tax for the last 4 tax years. In 2026/27:

Check each year individually — you may have overpaid in some years but not others.

Specific Overpayment Scenarios

Emergency Tax on a New Job

If you started a job without giving your employer a P45:

1. Your employer should have asked you to complete a starter checklist
2. If not done, you may be on an emergency code (0T/W1/M1 or BR)
3. Once HMRC updates your code, overpaid tax is refunded through your salary
4. If not corrected within 2-3 months, contact HMRC

Tax After Redundancy

The first £30,000 of a redundancy payment is tax-free. If tax was deducted from this amount:

1. Check your P45 from the former employer
2. If tax was wrongly deducted, contact HMRC
3. Any tax on earnings up to your leaving date should be correct on a cumulative basis

Marriage Allowance

If your partner earns under £12,570 and you’re a basic-rate taxpayer, you can transfer £1,260 of their personal allowance to you — saving £252/year. You can also backdate this for up to 4 years.

Apply at gov.uk/marriage-allowance.

Working From Home or Uniform Costs

You may be able to claim flat-rate tax relief for:

Beware of Tax Refund Scams

HMRC will never:

• Email or text you about a tax refund with a link
• Ask for bank details by email
• Request payment to process a refund

If you receive a suspicious communication, forward emails to phishing@hmrc.gov.uk and texts to 60599.

Related Guides

• What Happens If You Get the Wrong Tax Code
• Income Tax Guide
• What Happens If You Earn Over £100K
• Take Home Pay Calculator