Emergency Tax Code Checker
Check whether your tax code is an emergency code, and estimate how much extra tax you could be paying compared to the standard code.
Find this on your payslip or P45/P60. It's normally shown next to your National Insurance number.
⚠ Emergency Code Detected
This code has a W1/M1 (Week 1 / Month 1) marker, which ignores your cumulative earnings for the year and taxes each pay period in isolation — often resulting in overpayment early in the year.
Emergency tax codes are often temporary — HMRC usually corrects them automatically once your employer has full details (such as a P45 from a previous job), and any overpaid tax is refunded through your pay or a tax rebate. If your code hasn't updated after a couple of pay periods, contact HMRC directly.
What counts as an emergency tax code?
An emergency tax code is typically applied when HMRC doesn't yet have complete information about your income — for example, when you start a new job without a P45, take on a second job, or begin receiving a pension alongside your salary. Common emergency codes include BR (basic rate on all income), 0T (no Personal Allowance), and any code with a W1 or M1 suffix, which taxes each pay period in isolation rather than cumulatively across the tax year.
Being on an emergency code for a short time is normal and usually self-corrects once your employer has full details. If it persists, HMRC can issue a corrected tax code, and any tax you've overpaid is typically refunded automatically through your payslip or as a rebate.