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.
Being placed on an emergency tax code is a common, stressful, and frustrating issue that affects millions of UK workers. This most frequently happens after starting a new job, returning to work after a career break, or adding a secondary employment. Because the emergency codes deduct tax without fully accounting for your personal allowances, you may find your first paycheck significantly lower than expected. In this comprehensive guide, we explain what emergency tax codes look like, why they are applied, and provide a step-by-step process to reclaim your overpaid tax.
What is an Emergency Tax Code?
An emergency tax code is a temporary tax code applied by your employer’s payroll system when HMRC has not yet provided them with your official coding notice (such as a P45) for the current tax year. The most common emergency codes for 2026/27 are:
- 1257L W1 (Week 1) or 1257L M1 (Month 1): This is the standard emergency code. While it technically grants you the standard £12,570 Personal Allowance, it does so on a non-cumulative basis. This means payroll calculates tax on that pay period in isolation, ignoring what you earned or paid in tax in previous months.
- BR (Basic Rate): All income from this source is taxed at a flat rate of 20% immediately. No Personal Allowance is applied. This is typically used if you have a second job or have not completed a starter checklist.
- 0T: No tax-free allowance is granted at all. Your earnings are taxed starting from the very first pound at 20%, 40%, or 45% depending on the value of the paycheck. This is applied if you start a job without providing proper starter information.
Why Did HMRC Put Me on Emergency Tax?
There are three common reasons why you might find an emergency tax code on your payslip:
- Starting a New Job Without a P45: If you did not receive a P45 from your previous employer, or if you did not hand it over to your new employer before payroll was run, your new employer will not know your previous year-to-date earnings.
- Missing New Starter Checklist: If you did not complete your new employer’s Starter Checklist (which replaced the old P46 form) to state your employment status, they must put you on the 0T or BR emergency code.
- Starting Work Mid-Way Through the Year: If you start your first job of the tax year several months after April, payroll needs guidance on how to allocate your accrued personal allowance, which may trigger an emergency code until HMRC synchronizes your records.
Step-by-Step Guide to Claiming an Emergency Tax Refund
Overpaying tax due to an emergency code is temporary, and **you are legally entitled to a full refund of any overpaid tax**. Here is how to get your refund step-by-step:
- Complete the Starter Checklist: If you haven’t already, ask your employer’s HR department for a Starter Checklist. Fill it out and return it immediately.
- Wait for the Automatic Refund (Most Common): Once your new employer submits your starter information to HMRC, HMRC will calculate your correct cumulative tax code and issue a digital tax notice (P6T) to your employer. On your next pay cycle, your payroll software will apply the cumulative code. Any tax you overpaid in previous months will be automatically calculated and **refunded as a tax credit on your next payslip**.
- Contact HMRC Directly: If your tax code does not update after two pay cycles, log into your **HMRC Personal Tax Account** online or call HMRC on 0300 200 3300. Give them your new employer’s PAYE reference number (found on your payslip) and details of your estimated annual earnings. HMRC will update your code and instruct your employer to issue the refund.
- End-of-Year Reconciliation: If you leave your job before the refund is issued, or if the tax year ends, HMRC will reconcile your records automatically. They will send you a **P800 Tax Calculation letter** between June and November, which allows you to claim the refund online via bank transfer.
To estimate your take-home pay while on an emergency tax code and calculate the tax refund you are owed, use our Emergency Tax Calculator.
Frequently Asked Questions (FAQ)
Q: What is the difference between cumulative and non-cumulative tax codes?
A: Cumulative tax codes (the standard) look at your total year-to-date earnings and ensure your allowances are spread evenly over the 12 months. If you earn less in month 1, your allowance rolls forward. Non-cumulative codes (indicated by W1 or M1) treat each paycheck in isolation. If you earn £3,000 in month 1, you are taxed as if you will earn £36,000 annually, ignoring any previous unemployed months.
Q: How long does an emergency tax refund take?
A: If the refund is processed through your employer’s payroll, it is instant and will be added to your next regular salary payment. If the refund is claimed after the tax year ends via a P800 notice, it takes 3 to 5 working days to reach your bank account after submitting your claim online.
Q: Will I pay higher National Insurance on an emergency tax code?
A: No. Employee National Insurance contributions are calculated on each pay period in isolation and do not use cumulative coding. Therefore, being on an emergency tax code does not affect your National Insurance deductions, only your Income Tax.