HMRC is writing to UK households with new tax codes for the forthcoming tax year, now April is underway, and the financial year has started.
HMRC has issued a warning over tax codes that UK households need to get off as soon as possible. HMRC is writing to UK households with new tax codes for the forthcoming tax year, now April is underway, and the financial year has started.
But workers are being warned codes ending with W1, M1 or X are emergency tax codes. Emergency tax codes are typically assigned to individuals if HMRC lacks essential details about your income, such as when changing jobs, starting work with an employer after being self-employed, or receiving a state pension.
These codes are temporary, so it’s vital for those who notice this on their payslips to ensure it gets changed as soon as possible. You usually get put on an emergency tax code because your correct tax code is not available to HMRC, so you end up paying more tax than you need to.
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It’s important to understand that this is a temporary measure until you can be put on the correct tax code or until the end of the tax year. When you’re assigned an emergency tax code, you usually don’t receive any tax-free personal allowance, meaning you will pay too much income tax.
f you’ve overpaid tax due to an emergency tax code, there are several ways to reclaim the excess amount. To start, if HMRC issues a P800 tax calculation showing that you’re owed a refund, the accompanying letter will outline how the repayment will be made.
Refunds are typically processed via bank transfer directly to your account, often through your online Personal Tax Account, or cheque, sent to your registered address, or credit towards future tax, in some cases.
Before accepting the refund, it’s important to review the calculations in the P800 and compare them with your own records (such as payslips or P45/P60 forms). If there’s a discrepancy and HMRC overpays you, failing to report it can lead to a penalty—and you’ll be required to repay the excess.
If you suspect you’ve overpaid tax during the current 2025/26 tax year, but haven’t received a P800 notice, the issue may be related to your tax code. In this case, you don’t need to wait for HMRC to contact you—you can take action.
It’s best to do request a refund before the end of the tax year, to ensure any correction is made promptly.