What Is an Emergency Tax Code and How Do You Fix It?

Started a new job and being taxed a lot more than you expected? You’re probably on an emergency tax code. Here’s what it means, why it happens, and exactly how to fix it.

What is an emergency tax code?

An emergency tax code is applied by your employer when they don’t have enough information about your tax situation to use a permanent code. The most common emergency codes are:

• 1257L W1 — week 1 basis
• 1257L M1 — month 1 basis
• 1257L X — non-cumulative

The W1 or M1 suffix means your tax is calculated on a non-cumulative basis — each pay period is treated in isolation rather than as part of a running total for the year. This can result in overpaying tax, especially if your earnings vary month to month.

Why have you been put on emergency tax?

Emergency tax is applied when HMRC doesn’t have the information needed to issue a permanent code to your employer. Common reasons:

• You started a new job without providing a P45 from your previous employer
• It’s your first job and you’ve never been on PAYE before
• You’ve been self-employed and are returning to employment
• There was a delay in HMRC processing your information from a previous employer

How emergency tax affects your pay

On a standard emergency code like 1257L M1, you still receive the standard personal allowance — so it’s not as bad as a BR code (which gives no allowance at all). However, because it’s non-cumulative, you don’t benefit from unused allowances from earlier months. If you started part-way through the tax year, you may pay more tax than you should.

How to fix an emergency tax code

1. Give your employer your P45 — if you have one from your previous job, hand it to your new employer’s payroll department. They’ll use it to update your code
2. Complete a Starter Checklist — if you don’t have a P45 (first job, self-employment etc.), complete a Starter Checklist for your employer. This tells HMRC what situation you’re in and allows them to issue the correct code
3. Contact HMRC directly — call 0300 200 3300 or use your Personal Tax Account at gov.uk to check and update your tax code. HMRC will then issue the correct code to your employer

Will you get a refund?

If you’ve been on an emergency code and overpaid tax, the refund is usually applied automatically once the correct code is issued — your tax deductions will reduce in subsequent months to compensate. If the tax year has ended before the correction is made, HMRC may issue a direct rebate.

Frequently asked questions

How long does emergency tax last?

It should resolve within a few pay periods once your employer has your P45 or starter checklist. If it’s been more than 2–3 months and your code hasn’t updated, contact HMRC directly.

Is 1257L W1 the same as BR?

No — 1257L W1 still gives you a personal allowance (just applied weekly rather than cumulatively). BR gives no personal allowance at all and taxes everything at 20%. Both can mean overpaying — but BR is more severe.

Can I claim back emergency tax?

Yes. Once on the correct code, any overpaid tax is usually repaid through reduced deductions in future months. If the tax year ends before correction, claim through your HMRC Personal Tax Account or by writing to HMRC.

What if I’m still on an emergency code at year end?

Your P60 will show the emergency code used at 5 April. Your tax figures may be incorrect. Contact HMRC to investigate and arrange a refund of any overpaid tax.

Will this affect my P60?

If you’re on an emergency code at 5 April (year end), the P60 will show that code. The tax deducted on your P60 may be higher than it should have been. HMRC can correct this and issue a refund.

This post is for general information only and does not constitute financial or tax advice.