Emergency Tax Calculator
Check if you are overpaying tax. Estimate your potential refund based on BR, D0, D1, 0T, or 1257L W1/M1 emergency tax codes.
Calculate Your Tax Overpayment
Enter your gross pay and the emergency tax code shown on your payslip to instantly estimate how much tax you are overpaying compared to a standard 1257L code.
Payroll Details
Enter figures from your latest payslip
Tax Evaluation
Estimated deduction vs. expected normal tax
Understanding Emergency Tax Codes
A breakdown of common emergency tax codes and how they affect your take-home pay.
| Tax Code | Meaning | Tax Applied |
|---|---|---|
| 1257L W1 / M1 | Non-cumulative standard code. | Normal rates, but tax-free allowance does not build up. |
| BR | Basic Rate emergency code. | 20% tax on all income, no tax-free allowance. |
| D0 | Higher Rate emergency code. | 40% tax on all income, no tax-free allowance. |
| D1 | Additional Rate emergency code. | 45% tax on all income, no tax-free allowance. |
| 0T | All income is taxable. | Taxed at 20%, 40%, and 45% as income rises, with zero personal allowance. |
Emergency Tax FAQ
Everything you need to know about identifying and reclaiming emergency tax in the UK.
Emergency tax is applied when HMRC does not have enough information about your income to issue your correct tax code. This often happens when you start a new job, return to work, or receive a company pension without providing a P45. You may be placed on a ‘Week 1/Month 1’ (W1/M1) code or a flat-rate code like BR, D0, D1, or 0T.
Check your payslip. If your tax code ends with ‘W1’ or ‘M1’ (e.g., 1257L W1), or if it is a non-standard code like BR (Basic Rate), D0 (Higher Rate), D1 (Additional Rate), or 0T, you are likely being taxed on an emergency basis.
First, provide your P45 to your new employer or update your details via your HMRC Personal Tax Account. If you have overpaid, your employer may adjust your tax code to refund you through your payroll. Alternatively, HMRC will automatically calculate any overpayment at the end of the tax year and issue a P800 refund or adjust your next year’s tax code.
W1 (Week 1) or M1 (Month 1) means your tax is calculated on a ‘non-cumulative’ basis. You only receive 1/52nd or 1/12th of your annual tax-free personal allowance for that specific pay period, rather than the allowance building up over the year. This often leads to overpayment in subsequent pay periods.