Emergency Tax Code: What It Means for Your Pay

Seeing money missing from your first payslip at a new job is a shock. An emergency tax code is the most common reason.

This temporary code is called an emergency tax code. HMRC issues it when your employer cannot get your correct code in time.

Until the correct code is in place, you may pay more income tax than you owe. The difference can be significant, especially if the code stays in place for several pay periods.

Each year, thousands of UK workers encounter the emergency tax code problem. It is most common when starting a new job, taking on a second income, or moving into PAYE from self-employment.

In most cases any tax overpaid on an emergency tax code is refundable. Acting promptly limits what you overpay and makes a refund from HMRC straightforward to claim.

This guide explains what an emergency tax code is and why HMRC issues one. It also covers how to correct it and how to recover any tax you have overpaid.

Emergency tax codes explained

An emergency tax code is issued by HMRC when your employer does not hold your correct code. It acts as a placeholder until HMRC can supply the right one.

As an example the standard code for the 2026/27 tax year is 1257L. It applies your full personal allowance before any income tax is calculated.

Codes ending in W1, M1, or X are the most common emergency variants. These work on a non-cumulative basis, calculating tax for each pay period separately.

Because each period is treated in isolation, overpayments in one month are not corrected in the next. You can carry on overpaying until the code changes.

BR and OT codes can also serve as emergency tax codes. A BR code applies 20% to all earnings from that source with no personal allowance for it.

An OT code removes the personal allowance from that income source. It then taxes earnings at the rate matching your total income level.

What an emergency tax code looks like on your payslip

Check the tax code field on your payslip. It usually sits in the deductions or earnings section.

If you see any of the following entries, you are likely on an emergency code.

• W1 — used for employees paid on a weekly basis.
• M1 — used for employees paid on a monthly basis.
• X — a non-cumulative code where weekly or monthly basis does not apply.
• BR — basic rate tax at 20% with no personal allowance on that income.
• OT — no personal allowance; tax rate reflects your total earnings level.

W1 stands for Week 1 and M1 for Month 1, both referring to the non-cumulative calculation basis. Each pay period is taxed as if it were the first of the year.

To check your current code, visit your Personal Tax Account on GOV.UK or use the HMRC app. Your employer’s payroll team can also confirm the code they are using.

What the codes mean for your take-home pay

How much extra tax you pay depends on which code applies. It also depends on what information HMRC currently holds about your income.

A 1257L W1 or M1 code keeps your personal allowance but loses its cumulative effect over the tax year. Overpayments build up if your earnings vary between pay periods.

Under a BR code, 20% is deducted from all earnings at that source with no allowance applied. On monthly earnings of £2,000, that means £400 in tax before any threshold.

An OT code applies your marginal rate — 20%, 40%, or 45% — with no personal allowance for that income source. Your allowance is not lost entirely, though.

It continues to apply to your other income, under whichever tax code covers that employment or pension.

Emergency codes also ignore tax reliefs you may be entitled to. Uniform relief, home working relief, and professional fee deductions are excluded until the correct code is issued.

Reasons you may get a temporary code

HMRC issues a temporary code when it cannot verify your tax position in time. This most often happens at the start of a new job or after a change in your income.

Not having a P45 to give your new employer is the most common cause. Without it, there is no basis for calculating the right code from the start.

Other situations that can trigger a temporary code include:

• Starting a second job. Your personal allowance is already allocated to your main employment. The second employer may receive a BR or OT code for that income.
• Moving from self-employment into PAYE work. HMRC may not hold a current record, which delays the issue of the right code.
• Beginning to receive the State Pension while still employed. HMRC needs time to adjust your coding for both sources of income.
• Returning to the UK after working abroad. HMRC may not yet have up-to-date details of your income on record.

In each situation the temporary code is exactly that — temporary. Once HMRC has the information it needs, it updates your emergency tax code and corrects your deductions going forward.

How to change your emergency tax code

The right steps depend on why you have an emergency tax code. Acting as soon as you spot it reduces the amount of overpaid tax you accumulate.

If you have started a new job

Hand your new employer the P45 from your previous job as soon as you can. It holds the information HMRC needs to issue your correct code.

Your previous employer sends Part 1 of the P45 to HMRC directly. Give Parts 2 and 3 to your new employer without delay.

Once processed, HMRC sends an updated code to you and your employer. You should not normally need to contact HMRC if this goes smoothly.

If you do not have a P45

Complete a starter checklist and give it to your new employer if you cannot supply a P45. It provides the payroll information needed to apply the correct code.

The checklist works for a main job or a second part-time role. Give it to your employer before your first pay date for the best chance of the right code being used.

For other circumstances

If the code arose for another reason, use your Personal Tax Account or the HMRC app to query it. You can also check your income tax for the current year on GOV.UK.

HMRC can explain why the code was issued and update your record. A revised code should then be sent to your employer, and any overpayment corrected through your payslip.

Keeping emergency tax overpayments to a minimum

The best way to stop an emergency tax code building up overpayments is to act before your first pay date. Providing a P45 or starter checklist promptly is the most effective step.

If your employer has already processed one pay period using an emergency code, do not wait. Submit the missing document as soon as possible to limit further overpayments.

Your employer cannot change your tax code without instruction from HMRC. Once HMRC receives the updated information, it issues a new code and your deductions are corrected.

If you have a second job, make sure your personal allowance is correctly allocated to your main employment. Your second employer should normally receive a BR or OT code.

Check your payslip each pay period while an emergency code is in place. Catching an error early means fewer overpaid periods to recover through a later refund.

Getting a refund for overpaid tax

If an emergency tax code has caused you to overpay, you are entitled to that money back. HMRC handles many refunds automatically, but not all.

When your code is corrected within the same tax year, your employer adjusts future deductions. You should see the difference appear in your next payslip.

If the tax year ended before your code was corrected, the overpayment may not have been returned. Contact HMRC and ask them to review the affected year.

HMRC issues a P800 tax calculation when it finds you have overpaid tax. The P800 is available through your Personal Tax Account and the HMRC app, as well as by post.

Check the figures against your own payslip records before accepting them. Any discrepancy should be queried with HMRC directly.

HMRC can review up to four previous tax years for overpayments. If you think an earlier year was not corrected, check your Personal Tax Account or call HMRC to confirm.

How to claim your emergency tax refund

In most cases you do not need to make a formal claim for an emergency tax refund. HMRC corrects most overpayments through your employer once the right code is issued.

If the tax year closed before the code was corrected, contact HMRC by phone or through your Personal Tax Account. You can also write to HMRC or use the app to raise a query.

Once HMRC has reviewed the relevant years, the refund is normally paid by BACS to your bank account. Refunds for current-year corrections are usually processed within a few weeks.

If the emergency tax code covered more than one tax year, check each year separately. HMRC does not issue refunds for older years without a prompt from you.

An emergency tax code is a temporary measure, not a permanent problem.

In most cases it arises because HMRC is waiting for information from you or your employer. Providing a P45 or starter checklist is usually enough to resolve it.

Any tax overpaid because of an emergency tax code is recoverable. HMRC corrects most overpayments automatically once the correct code is in place.

You do not need to wait for HMRC to spot the problem. Checking your code and raising it with your employer or HMRC directly is the fastest route to a refund.

If you are unsure whether your tax code is correct, checking it costs nothing and takes only a few minutes. Acting sooner rather than later keeps any overpayment to a minimum.

Key Takeaways: Emergency Tax Code at a Glance

• An emergency tax code is temporary. HMRC issues it when your correct code is not yet available, usually at the start of a new job or after a change in income.
• It can cost you money. Depending on the code applied, you may pay tax on all earnings from that source with no personal allowance deducted first.
• A P45 or starter checklist is the quickest fix. Giving either to your new employer prompts HMRC to issue the correct code, usually without you contacting HMRC directly.
• Overpaid tax is refundable. Corrections within the same tax year are returned through your payslip. For older years, contact HMRC or log into your Personal Tax Account.
• Your P800 is now online. HMRC publishes P800 tax calculations through your Personal Tax Account and the HMRC app, as well as by post. Check the figures against your own records.
• Act promptly. The longer an emergency tax code stays in place, the more you may overpay. Catching it early makes recovery straightforward.

Frequently Asked Questions About Emergency Tax Codes

What is an emergency tax code and when is it used?

An emergency tax code is a temporary code issued by HMRC when it cannot supply your correct code to your employer. It is most common when starting a new job without a P45, taking a second job, or moving from self-employment into PAYE work. It stays in place until HMRC issues the correct one.

How do I know if I am on an emergency tax code in the UK?

Check the tax code box on your payslip. Codes showing 1257L W1, 1257L M1, 1257L X, BR, or OT usually indicate an emergency code. You can also check through your Personal Tax Account on GOV.UK or via the HMRC app. Contact HMRC to query it if the code does not match your circumstances.

How much extra tax will I pay on an emergency tax code?

The amount depends on which code applies. A BR code deducts a flat 20% from all earnings at that source with no personal allowance applied to it. An OT code applies your marginal rate — 20%, 40%, or 45% — again with no personal allowance for that income. A 1257L W1 or M1 code keeps your allowance but calculates tax on a non-cumulative basis, which can still produce overpayments.

Do I need to contact HMRC to get an emergency tax refund?

Not always. When your code is corrected in the same tax year, HMRC instructs your employer to return overpaid tax through your payslip. If the tax year has ended without a refund, contact HMRC or check your Personal Tax Account. A P800 tax calculation confirms the amount owed and is now available online through your Personal Tax Account and the HMRC app.

What should I do if I start a new job without a P45?

Complete a starter checklist and give it to your new employer as soon as possible, ideally before your first pay date. This provides the payroll information needed to apply the correct code. If an emergency code has already been used, submitting the checklist promptly should prompt HMRC to issue an updated code and correct your deductions going forward.