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Quick answer: | An emergency tax code means your Income Tax is calculate using only the pay you receive in the current week or month, rather than taking into account your income and tax paid earlier in the year. You're usually on an emergency tax code if your tax code ends with: W1 if you're paid weekly M1 if you're paid monthly X if your pay frequency varies |
Most PAYE tax codes work on a cumulative basis. This means your employer looks at your pay and tax position across the tax year so far when calculating how much Income Tax to deduct.
An emergency tax code works differently. It uses your current week’s or month’s pay in isolation. Previous earnings and tax paid earlier in the tax year aren’t included in that calculation.
This can mean you pay too much or too little tax temporarily.
The easiest way of knowing, is checking your payslip. If your tax code shows any of the following:
Ending | What it means |
Your tax is calculated on a week 1 basis | |
Your tax is calculate on a month 1 basis | |
Used in a non-cumulative basis, including where pay dates vary | |
Another way some payroll systems show a non-cumulative emergency code |
Then you're on an emergency tax code!
HMRC says that if your tax code doesn’t end in W1, M1, X or NONCUM, it isn’t an emergency tax code.
That distinction matters because codes such as BR or 0T aren’t automatically emergency tax codes.
1257L on its own isn’t an emergency tax code.
It is currently the tax code used for most people with one job or pension who receive the standard Personal Allowance. It becomes an emergency code when it is used with an emergency marker such as W1, M1 or X.
For example:
1257L = normally a standard cumulative tax code
1257L M1 = emergency tax code calculated on a month 1 basis
Your individual tax code can differ from 1257L depending on your circumstances.
| Code | Meaning |
| W1 | Week 1 basis |
| M1 | Month 1 basis |
| X | Non-cumulative basis |
All three effectively tell payroll to calculate tax only using the current pay period.
Previous earnings and tax already paid during the tax year are ignored.
This is why emergency tax codes are often called non-cumulative tax codes.
This is where most of the confusion comes from.
Under a normal cumulative tax code, HMRC looks at:
This creates a running calculation throughout the year.
If you've paid too much tax earlier in the year, it can automatically correct itself later.
Emergency tax codes don't do this.
Instead, every pay period is treated as though it's the first one of the tax year.
This means:
As a result, some people temporarily pay more tax than they should.
There are several common reasons where an emergency tax code can be used.
This is one of the most common reasons.
When you start a new job, your new employer needs information about your previous income and tax to operate PAYE correctly. If they don't have those details when they first pay you, an emergency tax code may be used temporarily.
Giving your new employer your P45, this is a separate document to your P60, can help them use the right information.
If you've never worked before, HMRC may not yet have enough information to determine the correct tax code.
Your employer will normally ask you to complete a Starter Checklist to help establish your tax position.
You've changed from self-employment to PAYE
Moving between different tax systems can occasionally trigger an emergency tax code while records are updated.
If you don’t have a P45 before your first payday, your employer may ask you to complete HMRC’s Starter Checklist.
The checklist gives your employer information about your employment, pension and benefits position so they can work out which tax code to use for your first pay.
This can apply if you’re:
starting your first job
starting your first job in the UK
returning to work after a break
starting employment after being self-employed
working for more than one employer
If you’ve already received your first pay, HMRC says you shouldn’t complete the Starter Checklist. You should use HMRC’s Check your Income Tax service to review your tax code and update incorrect details instead.
HMRC may also use an emergency tax code when you start receiving taxable company benefits or the State Pension.
In these circumstances, HMRC advises checking your tax code to make sure the benefit or State Pension has been included correctly.
Emergency tax can also affect some pension payments.
For example, pension providers commonly use a temporary or emergency tax code when certain pension lump sums are taken. Because the payment can initially be taxed as though you will receive the same amount regularly, more tax may be deducted than is ultimately due.
To understand why emergency tax sometimes causes overpayments, it helps to understand how PAYE normally works.
Your tax code is usually based on:
Under PAYE, your tax-free allowance is spread evenly across the year.
For example:
Emergency tax ignores much of the wider picture.
Instead, tax is calculated only on the current payment.
This can lead to temporary overpayments until HMRC updates your records.
Yes, although an emergency tax code doesn't automatically mean you've overpaid.
Example:
Imagine you've been unemployed for several months and then start a new job. Because your employer doesn't yet have complete information, you're placed on an emergency code. Payroll may treat your first month's earnings as though you'll earn the same amount every month for the rest of the year. That can result in more tax being deducted than necessary. Once HMRC receives updated information, the situation is normally corrected. In many cases, any overpaid tax is automatically refunded.
The first step is correcting the underlying tax code.
Often, this happens automatically once HMRC receives the information it needs.
If you've recently changed jobs, providing your P45 is usually the quickest fix.
If you don't have a P45, your employer can use a Starter Checklist to gather the information HMRC needs.
You can view your current tax code online and check whether HMRC's records are accurate.
If the code remains incorrect, you may need to contact HMRC directly.
If you've already paid too much tax, you may be entitled to a tax refund.
In some cases, HMRC automatically issues the repayment.
In others, you may need to submit a claim.
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HMRC uses several pieces of information to work out your code.
These include:
The more accurate the information HMRC receives, the more accurate your tax code will be.
Your tax code doesn't just consider your basic salary.
Taxable income can include:
Depending on your circumstances, pensions may also affect your tax code.
Yes, they can.
Benefits in kind are often reported through payroll or via a P11D.
Examples include:
If HMRC needs to collect tax on these benefits, it may adjust your tax code accordingly.
This doesn't automatically mean you're on emergency tax.
It simply means your code has been amended to account for additional taxable benefits.
A BR tax code is different from an emergency tax code, although people often confuse the two.
BR stands for Basic Rate.
It means all income from that job is taxed at 20%, with no Personal Allowance applied.
A BR code is commonly used for:
BR tax codes crop up in a few circumstances. Usually, it just means that your employer doesn't have enough information to give you anything else. For instance, this can happen if you haven't given them a P45 or P46 before starting work. The same thing can happen if you're moving from being self-employed to a PAYE job.
Not necessarily. The BR code really means that you aren't getting your tax-free personal allowance on that income. I If you've got more than one job, you only get the allowance on one of them. Keep in mind that if your Personal Allowance is being applied to a low-paid job, you might not get the full benefit of it. In that case, you should talk to RIFT about getting it transferred to your other source of income.
A K tax code is another code that often worries people.
A K code usually means:
Rather than reducing your tax-free allowance, HMRC effectively adds taxable income into the calculation.
K codes aren't emergency tax codes, but they can result in higher deductions from your pay.
In many cases, only a few weeks.
Once HMRC receives:
the correct code is usually issued.
However, problems can sometimes continue for months if information is missing or incorrect.
That's why it's important to check your payslips and tax code regularly.
It can, depending on the reason it was applied.
If you’ve recently started a job, HMRC will usually update the code once it receives the information it needs. That can take up to 35 days from your start date.
There are circumstances where an emergency code can remain for longer.
For example, HMRC says someone put on an emergency code after starting to receive company benefits or the State Pension may remain on it until the end of that tax year before moving onto a non-emergency code in the new tax year.
So it’s worth checking why the code has been applied rather than assuming every emergency code will disappear after the next payday.
When you claim your tax rebate with RIFT, our unique RIFT Guarantee means that you’ll never have to worry about the taxman reclaiming any of your money. So long as you give us full and accurate information, if HMRC disagrees with the amount we've claimed and asks for some money back, we'll pay it from our own pocket instead of yours. It won't cost you a penny!
Possibly.
You may be due a refund if:
Many people assume everything corrects itself automatically.
Often it does.
Sometimes it doesn't.
If you've spent a significant period on an incorrect emergency tax code, it may be worth checking whether you've overpaid.
Tax codes can feel confusing, but the good news is that emergency tax codes are usually temporary and relatively straightforward to fix once HMRC has the right information. If you're unsure whether your code is correct, or you're concerned you've paid too much tax, it's worth checking sooner rather than later.
An emergency tax code is a temporary tax code used when HMRC doesn't have enough information to calculate your correct tax code.
Look for W1, M1 or X at the end of your tax code.
No. It's usually a temporary administrative issue rather than a mistake by you.
Yes. If you've paid too much tax, you may be entitled to a refund.
Usually only until HMRC receives the information needed to calculate your correct code.
Yes. This is one of the most common reasons people receive an emergency tax code.
Often, yes. Providing your P45 gives your new employer the information needed to apply the correct tax code more quickly.
No. They're different tax codes, although both can sometimes appear when HMRC is missing information.