Published: June 2026 | Fact-Checked & Audited By: David Vance, CTA FCA (Chartered Tax Advisor & Accountant)
This guide is fully updated for the 2026/27 HMRC tax year. All calculations and tax rules have been audited against official UK legislation.
Starting a new job in the UK should be an exciting milestone, but it is frequently dampened when your first payslip arrives showing a much lower take-home pay than expected. This is usually due to the application of an emergency tax code (you can calculate your true tax liability and check for errors using our Emergency Tax Calculator). Understanding why emergency tax happens, how it is calculated, and what steps you must take to secure a refund is crucial for recovering your money.
What is an Emergency Tax Code?
Emergency tax codes are temporary codes applied by employers when HMRC has not yet provided a permanent tax code for an employee. This commonly occurs if you are starting your first job, changing employers without a P45 form, or returning to work after a break. These codes ensure that tax is collected, but they do not account for your full personal tax circumstances.
The emergency tax codes for the 2026/27 tax year are **1257 W1**, **1257 M1**, and **1257 X**. These codes indicate that your tax is calculated on a non-cumulative basis, meaning each week or month is treated in isolation, ignoring what you have earned or paid in tax earlier in the tax year.
Comparison Table: Cumulative vs. Non-Cumulative (W1/M1) Tax
| Tax Calculation Type | How It Works | Impact on New Starters |
|---|---|---|
| Cumulative Tax (Standard) | Looks at total earnings and tax paid year-to-date. Automatically adjust allowances. | Prevents overpayment; balances out tax fluctuations over the year. |
| Non-Cumulative (W1/M1) | Treats each pay period as if it is the first week/month of the tax year. | Can lead to overpaying tax if you had gaps in employment or lower pay earlier. |
| BR Code (Basic Rate) | Taxes all income at the basic rate (20%) from the first pound, with zero Personal Allowance. | Results in severe overpayment if this is your main or only source of income. |
How to Fix an Emergency Tax Code
To resolve an emergency tax code, HMRC must issue a revised coding notice to your employer. In most cases, this happens automatically when you complete a starter checklist (which replaced the old P46 form) or when your previous employer submits your P45 details to HMRC via the payroll system.
If the emergency code persists past your second payslip, you should log into your Personal Tax Account online or contact HMRC directly by phone. Once HMRC updates your code, they will send a dynamic tax code notice (P2) to you and your employer, prompting payroll to refund any overpaid tax in your next salary payment.
Frequently Asked Questions
Q: Why am I on an emergency tax code?
You are on an emergency tax code because HMRC has not yet provided your new employer with your correct tax details. This usually happens if you start a new job without submitting a P45 or starter checklist on time.
Q: How do I know if I am on emergency tax?
Look at the tax code section on your payslip for suffix codes like W1, M1, or X. If your code is listed as 1257L W1 or 1257L M1, you are paying emergency tax on a weekly or monthly basis.
Q: What does the BR tax code mean?
The BR tax code stands for Basic Rate and taxes all your income at 20% with no tax-free allowance. It is commonly applied to second jobs or when payroll has no information about your primary income.
Q: How long does emergency tax last?
Emergency tax typically lasts until your employer receives a new tax code instruction from HMRC. This usually takes 3 to 6 weeks, depending on when your payroll submits starter information.
Q: Will my emergency tax be refunded automatically?
Yes, any overpaid emergency tax is normally refunded automatically through your payslip once your code is corrected. Your next salary payment will show a lower tax deduction or a tax refund credit.
Q: What should I do if I don’t have a P45?
If you do not have a P45, you must fill out a Starter Checklist provided by your new employer. This form collects details about your current work situation so payroll can apply a temporary code.
Q: What does a 0T tax code mean on my payslip?
The 0T tax code means you have no personal allowance and all income is taxed at the standard rates. This code is used if you started work without completing a starter checklist or P45.
Q: Can I call HMRC to change my tax code faster?
Yes, calling HMRC or updating your details in the HMRC app can speed up the update process. Once updated, they will transmit the new tax code electronically to your employer’s payroll software.
Q: What happens if the tax year ends while I’m on emergency tax?
If the tax year ends, you cannot get the refund through payroll and must claim it directly from HMRC. HMRC will calculate your tax overpayment and send you a P800 refund letter during the summer.
Q: Do emergency tax codes affect National Insurance contributions?
No, emergency tax codes only affect your income tax deductions. National Insurance is always calculated based on your actual earnings in each specific pay period, regardless of your tax code.