P800 Tax Refund Estimator
Compare your actual tax deducted against your true legal liability to instantly estimate if HMRC owes you a refund. No login required.
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P800 Estimate
Balanced
Your tax paid perfectly matches your tax liability. No refund is due.
What Is a P800 Letter From HMRC?
A P800 is a tax calculation letter automatically generated by HMRC at the end of the tax year. It reconciles their records of your PAYE earnings against the actual tax you paid.
HMRC sends out millions of these letters between September and November every year. If you receive one, it means you have either paid too much tax (and are owed a refund) or paid too little tax (and owe HMRC money). If your tax was perfectly balanced, you will not receive a P800.
Why Might I Have Overpaid Tax?
PAYE (Pay As You Earn) is designed to spread your tax liability evenly across 12 months. However, the system is fragile and easily disrupted by changes in your employment status.
Wrong Tax Code
This is the #1 cause of overpayments. If your employer didn't have your correct details, they likely put you on an emergency tax code (like 1257L W1/M1). This prevents you from accessing your full annual tax-free allowance. If you suspect this happened to you, use our Wrong Tax Code Fix guide.
Starting or Leaving a Job Mid-Year
If you only worked for 6 months of the year, you probably paid tax on those 6 months as if you were going to earn that same salary all year. Because you didn't work the other 6 months, you likely didn't use up your full ยฃ12,570 Personal Allowance, resulting in a large overpayment.
Multiple Jobs in One Tax Year
If you worked two jobs simultaneously, your second job should have been placed on a "BR" (Basic Rate) tax code. If HMRC split your Personal Allowance incorrectly across the two jobs, it often results in the wrong amount of tax being deducted. You can verify your exact monthly liability using our Take-Home Pay Calculator.
How to Claim Your P800 Refund
If your P800 letter says you can claim online, do not wait for a cheque in the post. Log in to your HMRC Personal Tax Account using your Government Gateway ID. Navigate to the PAYE section and hit "Claim your refund".
Once you enter your bank details, the money is typically processed and deposited into your account within 5 working days. If you ignore the letter for 21 days, HMRC will eventually post you a cheque, but this can take up to 6 weeks.
Can I Claim a Refund Without a P800?
Absolutely. HMRC's automated system isn't perfect, and they often fail to issue a P800 even when an obvious overpayment has occurred.
If you have used our calculator above and it says you are owed a refund, you do not have to wait for HMRC. You can log into your Personal Tax Account and request a manual tax calculation, or call them directly. If you also have job expenses to claim (like uniform washing or mileage), you can wrap it all up using our Tax Rebate Calculator.
How Far Back Can I Claim a Tax Refund?
You can claim a tax refund for the current tax year, plus the 4 previous tax years. This is a strict statutory limit. If you discover an overpayment from 5 years ago, HMRC will not refund it.
For example, during the 2026/27 tax year (which ends at midnight on 5 April 2027), you can claim refunds going back to the 2022/23 tax year. Once the clock strikes midnight on April 5th, the 2022/23 tax year is closed forever.
Tax Overpayments