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Emergency tax refund: how overpaid tax is corrected and claimed

If you were on an emergency or 0T code, you may have paid more tax than you owed. HMRC corrects this through your pay where it can, and through a P800 letter after the tax year where it cannot.

Updated . Facts checked against GOV.UK on .

How the overpayment happens

Emergency codes, and the 0T code given to a new starter with no P45 or checklist, each tax a pay period on its own. With W1 or M1 you get one period’s share of the allowance each time, but any you do not use in a quiet week or month is lost. With 0T you get no allowance at all. Either way, the tax can end up higher than the total for the year needs.

Not every overpayment is caught in time. Some only come to light after the tax year ends on 5 April.

How it is corrected through your pay

HMRC usually updates your code within 35 days of you starting a job, once it has details from your new and previous employers. GOV.UK says you cannot get a refund until HMRC has your income details from your employer, pension provider or benefits office.

When HMRC sends the new code, GOV.UK says your employer will be asked to refund the difference in your pay. The timing depends on how you are paid.

  • Monthly pay: the new code should be used on your next pay or the one after.
  • Weekly pay: the new code should be used on your third pay.
  • It normally shows as a lower tax deduction on the payslip where the new code takes effect.

When a P800 is involved

HMRC checks your tax after the tax year ends. If it finds you paid too much or too little, it sends a P800 tax calculation letter. GOV.UK says the letter tells you how to get a refund or pay any tax you owe. Being put on the wrong tax code is one of the reasons HMRC gives for sending one. GOV.UK says the letters are sent out between June and March of the following tax year. If you complete a Self Assessment return you will not get one.

If your P800 says you are due a refund, you usually need to claim it. Claim through GOV.UK, the HMRC app or your personal tax account. Do not follow links in unexpected emails or texts that say you are owed a refund. The options are:

  • Online bank transfer: use the online service with the reference number from the P800 and your National Insurance number. GOV.UK says the money arrives in 5 working days.
  • Cheque: you can request one online. GOV.UK says a requested cheque takes 6 weeks.
  • If the letter says a cheque is coming, you do not need to claim. GOV.UK says it arrives within 14 days of the date on the letter.
  • Personal tax account or the HMRC app: also possible if you have a UK bank account.

If you have overpaid and have no letter

GOV.UK says that if you think you have paid too much and HMRC has not sent a tax calculation letter, you should find out how to claim a refund. The GOV.UK refund tool covers pay from a job and points you to the right steps. It does not process the claim itself.

If you are claiming on paper, form R38 asks for the tax year you want to claim for, and for your employer’s PAYE reference, if you have one (it is on your P60).

Overpaid tax can usually be claimed back for up to four tax years after the one it was paid in, so tax overpaid in 2022/23 would normally need claiming by 5 April 2027. HMRC will normally refuse claims for older years, so do not leave a year until the last moment.

What to check before you claim

Compare the P800 with your own records before you accept it. If you think an amount is wrong, contact HMRC and say which amount you think is wrong and what it should be.

  • The tax year on the letter, and the figures for pay and tax against your payslips and hours.
  • Whether you had another job in the same tax year, and what code it was on.
  • Whether your code is now 1257L, or still on W1, M1 or 0T.
  • Whether the letter says you are due a refund or owe tax. A letter that says you owe tax needs a different response.

Next steps

Work through these in order.

  • Check your code in your personal tax account or the HMRC app.
  • If your code is still an emergency code more than 35 days after you started, contact HMRC.
  • If your P800 says you are due a refund, follow the instructions in the letter.

Keeping a record

Keeping your own record of hours and pay makes a mismatch easier to spot. Logging your shifts in Shyft gives an estimate you can compare against your payslips, so a difference shows up early rather than at the end of the year.

Related guides

Sources

This is an estimate, not financial or tax advice. Your payslip is the final figure.