P800 Tax Refund Calculator 2026/27

A P800 is a tax calculation letter HMRC sends automatically when its records show you've paid the wrong amount of Income Tax through PAYE during the tax year — either too much (meaning you're due a refund) or too little (meaning you owe more). HMRC typically sends these between June and November, after the tax year has ended and their systems have reconciled your actual income against the tax you paid.

Common reasons for an overpayment include: having an incorrect tax code for part of the year (for example, after changing jobs and being put on an emergency code), having multiple jobs or pensions where the tax-free Personal Allowance wasn't split correctly, stopping work partway through the tax year, or having taxable benefits that changed but weren't reflected in your tax code in time.

Worked example: someone who left a job in July and didn't work again until the following January might have overpaid tax during the months they weren't earning, since PAYE assumes a steady income across the full tax year — HMRC's P800 reconciliation at year end would identify this and calculate a refund based on their actual annual income being lower than PAYE assumed.

If your P800 shows a refund, you can typically claim it online through your Personal Tax Account or it may be paid automatically to your bank details on file; if it shows you owe money, HMRC usually collects this by adjusting your tax code for the following year rather than requiring an immediate lump sum payment, unless the amount is large. This calculator gives an estimate of what you might be owed based on your figures — your actual P800 outcome depends on HMRC's full-year reconciliation of your specific tax code history.