UK Tax Rebate
Calculator 2026/27
Find out whether you have overpaid income tax this year and get an estimate of how much you could claim back from HMRC.
Find this on your payslip, P60 or P45
Why might you have overpaid income tax?
Most people pay tax through PAYE, where your employer deducts the right amount each month. However, overpayments are common in certain situations:
- Wrong tax code — if HMRC issues an incorrect code (e.g., using a basic rate emergency code instead of your actual code), you may pay more tax than necessary.
- Changing jobs — if you switched employers mid-year and had multiple employers apply the personal allowance, or conversely had neither apply it, you may have an overpayment or underpayment.
- Part-year working — if you only worked for part of the tax year, you will have used less than your full personal allowance of £12,570 but may have had tax deducted as though you were working all year.
- Maternity or sick leave — periods on reduced or no pay can result in an overpayment of tax paid in earlier months.
How to claim a tax rebate
HMRC reviews tax paid at the end of each year and sends a P800 letter if they identify an overpayment. You can also claim proactively through your Government Gateway account, by calling HMRC on 0300 200 3300, or via self-assessment if you complete a tax return.
Related calculators
The best way to check your overall tax position is with our income tax calculator which applies the correct personal allowance and bands. The main salary calculator shows income tax, National Insurance and all deductions together so you can see what should have been deducted. Our tax band calculator confirms which rate applies to each slice of your income. If over-payment was caused by a pension contribution change, our pension calculator shows the impact on taxable income. Claiming child benefit alongside a high income? Our child benefit tax calculator checks whether you have a High Income Child Benefit Charge liability. The National Insurance calculator confirms NI deductions were also correct.
Frequently asked questions
Signs of overpayment include receiving a P800 from HMRC, having an emergency tax code (BR, 0T, or W1/M1), working part of the year, changing jobs mid-year, or having too much tax deducted in earlier months before a pay reduction. You can check using HMRC's online services or this calculator.
If HMRC identify an overpayment they will send a P800 tax calculation after the tax year ends. If you believe you have overpaid, you can claim online via your Government Gateway account, call HMRC on 0300 200 3300, or use self-assessment. You can claim back overpaid tax from the last 4 tax years.
If HMRC processes your rebate automatically following a P800 it typically takes 5 to 6 weeks. If you claim online through Government Gateway and are registered for a bank transfer, the money usually arrives within 5 working days. Cheques sent by post take longer and are being phased out.
Yes. You can claim a tax rebate for up to 4 previous tax years. In 2026/27 you can claim back to 2022/23. Claims for years before that are generally not accepted. It is always worth checking — many people are unaware of overpayments from several years ago.