Why Have I Been Put on an Emergency Tax Code

Introduction

An emergency tax code is a temporary code that HMRC assigns when it does not have enough information about your income or previous employment. It ensures you pay the right amount of tax for the current pay period, but it may mean you are not receiving your full personal allowance straight away.

Emergency tax codes are common when starting a new job, returning to work after a break, or working for multiple employers. The good news is that they can be easily corrected once HMRC has your full details.

What is an emergency tax code

A tax code tells your employer how much tax-free income you are entitled to before PAYE (Pay As You Earn) deductions are made. Most employees in the UK have the standard tax code 1257L, which gives them £12,570 of tax-free income each year.

If HMRC does not have enough information to apply your correct tax code, it will use an emergency code instead. These codes make sure tax is still collected, but they do not always take your full annual allowance into account.

Common emergency tax codes include:

1257L W1/M1: Non-cumulative, giving you only a week’s or month’s worth of tax-free allowance each pay period.

0T W1/M1: No personal allowance applied, meaning all earnings are taxed at basic, higher, or additional rates.

These codes are not permanent and will usually be updated automatically once HMRC receives the right information.

Why you have been put on an emergency tax code

HMRC uses emergency tax codes when it cannot confirm your previous pay and tax details. Common reasons include:

Starting a new job without a P45
If you start a new job and your previous employer has not provided you with a P45, your new employer will not know how much tax you have already paid that year. Without this information, they must apply an emergency tax code until HMRC updates your record.

Changing jobs mid-year
Even if you hand over a P45, there can sometimes be a delay while HMRC processes the data from your previous job. During this time, your new employer might apply an emergency code as a temporary measure.

Starting your first job
If this is your first job, HMRC has no prior tax record for you, so an emergency tax code is used until your employment details are established.

Returning to work after a break
If you have been unemployed, self-employed, or on extended leave (such as parental or sabbatical leave), HMRC may not have current income information and will apply an emergency tax code until your situation is updated.

Having more than one job or pension
If you have more than one source of income, HMRC must decide where to apply your personal allowance. If it is unclear which job or pension should receive the allowance, an emergency code may be used temporarily.

Incorrect or outdated personal details
If your name, address, or National Insurance number is incorrect on HMRC’s records, it can lead to a temporary tax code until the issue is resolved.

How an emergency tax code affects your pay

When you are on an emergency tax code, your employer calculates tax as if each payday is the first one of the tax year. This means:

You get one week’s or one month’s worth of tax-free allowance at a time.

HMRC ignores previous earnings when working out your tax.

You may pay slightly more tax than necessary.

The effect varies depending on the emergency code used. If your code is 0T, you pay tax on all earnings with no allowance at all, which results in a larger deduction.

Once your code is corrected, HMRC or your employer will refund any overpaid tax automatically through your payslip or after the end of the tax year.

How to fix an emergency tax code

Emergency tax codes are temporary and usually correct themselves once HMRC receives the missing information. However, you can speed up the process by taking the following steps:

Check your P45
If you have left a previous job, give your P45 to your new employer as soon as possible. It contains details of your income and tax paid so far in the tax year, allowing HMRC to calculate your correct code.

Complete a starter checklist
If you do not have a P45, your new employer should ask you to complete a starter checklist (previously called a P46). This form provides HMRC with basic information about your employment history.

Log in to your Personal Tax Account
You can check your current tax code and employment details on GOV.UK using your Personal Tax Account. If something looks wrong, you can update your information directly online.

Contact HMRC
If your employer has your correct details but your tax code still seems incorrect, contact HMRC on 0300 200 3300. They can review your records and issue an updated code to your employer.

Wait for your refund
Once HMRC updates your tax code, any overpaid tax will be automatically refunded through your employer’s payroll or, if you have already left the job, sent directly by HMRC.

How long it lasts

An emergency tax code usually applies only for a short period, typically until HMRC receives and processes your correct pay and tax information. This could take a few weeks or a couple of months depending on how quickly the data is updated.

If you stay on an emergency code for more than two or three pay periods, contact HMRC to check that your records are up to date.

Preventing future tax code problems

Always keep your P45 when changing jobs and give it to your new employer promptly.

Check your payslips regularly to make sure your tax code is correct.

Keep HMRC informed of changes to your employment, address, or personal details.

Register for a Personal Tax Account to monitor your income and tax records online.

Common mistakes to avoid

Ignoring your payslip and not noticing an emergency tax code.

Waiting too long to send your P45 or starter checklist.

Assuming your employer can correct the code without HMRC’s approval.

Failing to update HMRC when you have more than one job or pension.

Conclusion

Being placed on an emergency tax code is a common and temporary situation. It usually happens when HMRC does not yet have enough information about your employment or income. While it can cause you to pay slightly more tax initially, the issue is easily fixed once your records are updated.

Check your tax code on your payslip or online, provide your P45 to your employer, and contact HMRC if the problem persists. Any overpaid tax will be refunded automatically, ensuring you pay the correct amount by the end of the tax year.