Emergency tax codes: why you have one and how to fix it

An emergency tax code is what HMRC puts you on when it does not have enough information about your income to work out your tax properly. The code for 2026/27 is 1257L, the same as the normal code for most people, but with a W1, M1 or X added to the end¹. Those letters are the giveaway: they mean each payment is taxed on its own, as if it were a month of your yearly pay, rather than across the whole year².

The effect is that you usually pay more tax than you owe. The code gives you one twelfth of the Personal Allowance if you are paid monthly, on a non-cumulative basis, and taxes everything above that³. It is temporary, and it switches to the right code once HMRC has the missing details, with any overpaid tax refunded⁴.

The most common trigger is starting a new job, or taking a first payment from a pension. Both leave a gap in your tax records that HMRC fills with an emergency code until the paperwork catches up.

What an emergency tax code is and why you have one

Your tax code is issued by HMRC, not by your employer⁷. It tells your employer or pension provider how much tax-free income to give you before tax starts. When HMRC does not have enough details about how much tax you need to pay, it may apply an emergency tax code to your salary instead⁶. Emergency codes are applied automatically, but only as a temporary measure⁶.

The most common time to find you have been put on one is when you have just started working for a new employer⁶. In your first job, or on your first day in a new job, you may be given an emergency tax code because your employer does not yet have all your tax information⁴. It usually means HMRC is waiting for leaving details from your old employer, or that you have not filled in the new starter checklist¹. HMRC may also put you on a temporary emergency code if it does not get your income details in time, or if you decide not to share that information with your new employer⁸.

There is a separate code, 0T, that applies when your earnings exceed the basic rate tax band or your employer has not given HMRC the details it needs⁶. That is a different situation from the W1, M1 and X suffixes, and it is worth knowing which one you have before you try to fix it.

How to spot an emergency code on your payslip

The emergency tax code is written on your payslip, and you can generally find it near your National Insurance number⁶. If your tax code changes to have a W1, M1 or X at the end, you are on what is called an emergency tax code¹.

The code for 2026/27 is 1257L¹. In 2024-25 the most common tax code was also 1257L, so the number itself is not the warning sign⁹. The suffix is. M1 is applied if you are paid monthly, while W1 is used if you are paid weekly⁶. In 2026/27 an emergency code might look like this: 1257L M1².

If you have been at a new job for more than three months and you are still paying emergency tax, that is worth checking⁶.

An emergency code taxes each payment as if it were one month of your yearly pay

This is the part that catches people out. The emergency code assumes you receive the same amount each month, and treats the sum you receive as one twelfth of your annual income, so more tax than is due will be deducted⁵. It gives you one twelfth of the Personal Allowance if you are paid monthly, on a non-cumulative basis, and you are taxed on all income above that amount³.

The current emergency tax code is 1257L (M1), which means you get a tax-free sum of £1,047.50 and anything over that is taxed¹⁰. Because the calculation is non-cumulative, each payment is judged on its own. A single large payment in one month is therefore taxed as though you earned that amount every month of the year, which pushes it into higher bands than your actual annual income would reach.

The same rule applies to pension income. Your provider is required to deduct tax as if you took the same amount every month¹¹.

Emergency tax on your first pension withdrawal

Pension providers typically use temporary or emergency tax codes when you take your first lump sum¹². When you take your first withdrawal, you will probably be taxed on an emergency tax code¹³. That could mean you overpay, with the overpayment refunded after the tax year end¹⁴.

If you withdraw a taxable lump sum from your pension, an emergency tax rate is charged until your individual tax code is received from HMRC directly¹⁵. The same applies to drawdown calculators, which apply an emergency Month 1 tax code, giving you only one twelfth of the available allowances in line with HMRC guidelines¹⁶.

The practical effect is that a large one-off withdrawal may have an emergency tax code applied, resulting in too much tax being taken⁵. If you are taking a whole pot, the tax is deducted at source before the money reaches you, so the overpayment has to be reclaimed rather than simply not paid.

How to fix an emergency tax code and get overpaid tax back

You can check and claim for a refund online on GOV.UK, or on the HMRC app, or by asking HMRC to send you a cheque¹. HMRC may also reduce the tax collected from your future wages instead of sending a refund¹.

To correct the code itself, you can use HMRC's online Income Tax checker, or call 0300 200 3300⁶. Once HMRC has all the information to set you on the right tax code, you will be refunded any tax you have overpaid¹. If your emergency tax code means you have paid too much tax, HMRC will send you a tax rebate⁶. HMRC will eventually refund the overpaid tax, usually at the end of the tax year, but you can get your money back within 30 days by submitting the relevant form⁵.

If you think the tax is wrong, your tax code may be incorrect¹⁶. Payslips, P60s, invoices or Construction Industry Scheme deduction statements can help show why a correction is wrong, though the evidence is optional¹⁷.

Who decides your tax code, and how PAYE fits in

PAYE, or pay as you earn, refers to income tax deducted from your salary before you receive it¹⁸. Introduced in 1944, it is now the way most employees pay income tax¹⁸. Your employer works out how much tax and National Insurance you owe, takes it from your wages before you are paid, and sends the money to HMRC⁴. It is the most common method of paying income tax if you are employed¹⁹.

Within that system, HMRC issues the code and your employer operates it⁷. That matters when something goes wrong: your employer cannot change your code on their own initiative, so a correction has to come from HMRC. If you have more than one job, HMRC splits your allowance between them, and a new job can leave the old one still holding part of it⁸.

If you cannot afford the tax while you wait

An emergency code takes more from each payment, which can leave a gap before the refund arrives. If that pushes you into difficulty, free and impartial help is available. MoneyHelper, the government-backed service, suggests an emergency fund covering three to six months of essential outgoings²⁰.

If you are behind on essential bills, there are routes to breathing space and to writing off debt, and free debt advice charities can talk through your options. If you are in Wales, an Emergency Assistance Payment may be available to help with costs such as food, and you can ask for the decision to be reviewed if you do not agree with it²¹.