Answers · UK 2025/26

How do I claim back emergency tax in the UK?

Emergency tax usually corrects itself within a pay period or two once your employer receives your correct tax code, and any overpayment is automatically refunded through your payslip. If it does not resolve automatically -- for example if you have left the job -- you can claim a refund directly from HMRC via your Personal Tax Account or by post.

Last updated: 2 July 2026Last reviewed: 2 July 2026How we verify

Full answer

Emergency tax happens when your employer does not yet have the information needed to apply your correct, cumulative tax code, most commonly when starting a new job without a P45 from your previous employer, or when starting a job partway through the tax year with incomplete information. **Why it happens** Without a P45 or a completed starter checklist providing your tax history for the year, your employer must apply an emergency tax code (often on a "Month 1" or "Week 1" non-cumulative basis) which does not account for your Personal Allowance built up earlier in the tax year, resulting in more tax being deducted than you actually owe. **Automatic correction** In most cases, once HMRC receives updated information (either from your P45, your starter checklist, or their own records) and issues your employer the correct cumulative tax code, the overpaid tax is automatically refunded through your next payslip, since PAYE cumulative calculations "catch up" and correct for the earlier overpayment. **If you've left the job** If the emergency tax situation was never corrected because you left that job before it resolved, or the tax year ended before correction, you may need to actively claim the refund from HMRC rather than waiting for automatic correction -- this typically requires either checking your Personal Tax Account online for a P800 calculation, or contacting HMRC directly if no automatic reconciliation has happened. **Using form P50 if unemployed** If you have stopped working and do not expect to work again in that tax year, you can claim an in-year refund using form P50, since without this you might otherwise wait until the following year for the automatic reconciliation to catch up. **Providing a P45 promptly** The simplest way to avoid emergency tax altogether when starting a new job is to give your new employer your P45 from your previous job as soon as possible, or complete the HMRC starter checklist accurately if you do not have a P45 -- this lets your new employer apply the correct code from the start rather than an emergency basis. **Worked example** Someone starts a new job in July without a P45, and is put on an emergency Month 1 tax code, meaning they get 1/12th of the annual Personal Allowance applied each month rather than the correct cumulative amount that would reflect the unused allowance from April to June. Once HMRC issues the correct code (perhaps in September), the next payslip includes a lump sum refund correcting for the earlier overpayment. **Practical tip** Check your payslip's tax code against the standard code for your circumstances (1257L is standard for most people with no adjustments in 2026/27) -- if you see a code ending in "W1" or "M1" (Week 1/Month 1 basis) for more than a couple of pay periods, contact HMRC or your payroll department to check why the cumulative code has not yet been applied.