An emergency tax code is a temporary tax code used when HMRC or your employer doesn't yet have enough information to calculate your tax in the normal way.
That doesn't automatically mean something has gone wrong, and it doesn't necessarily mean you'll pay too much tax. It simply means PAYE has to work with the information currently available.
Once HMRC receives the missing details, it will usually issue the correct tax code and future payslips should be adjusted automatically.
If this is your first job in the UK, it may also help to read Your First Adult Documents Pack, which explains the main documents and numbers you'll come across when you start working.
What is an emergency tax code?
An emergency tax code is a temporary tax code used when HMRC or your employer doesn't yet have enough information to calculate your Income Tax in the normal way.
That doesn't automatically mean something has gone wrong, and it doesn't necessarily mean you'll pay too much tax. It simply means the PAYE (Pay As You Earn) system has to work with the information currently available until HMRC receives the missing details.
Once that happens, HMRC will usually issue the correct tax code to your employer and future payslips should be adjusted automatically.
Emergency tax codes are most common when you:
- start your first UK job
- change employers
- return to work after a long break
- have more than one job
- haven't given your employer a P45
- complete a Starter Checklist because you don't have a P45
Why does this happen?
PAYE is designed to collect Income Tax throughout the year, rather than all at once at the end of it. To calculate the right amount, HMRC needs information such as:
- how much you've already earned during the current tax year
- how much tax you've already paid
- whether you have another job
- whether you're receiving a pension or taxable benefits
- which employer should receive your Personal Allowance
If some of that information is missing, payroll can't simply guess. Instead, they have to use the tax code HMRC allows for that situation until your employment record has been updated.
In other words, an emergency tax code is usually just a placeholder rather than a sign that something has gone wrong.
Common situations where emergency tax codes appear
You're starting your first job
This is one of the most common reasons for an emergency tax code.
Because you don't have a previous employer in the current tax year, payroll may need to rely on the information you provide on your Starter Checklist until HMRC confirms the correct tax code.
You've changed jobs
When you leave a job, your employer should give you a P45. This tells your new employer how much you've earned so far during the tax year, how much tax you've already paid and which tax code you were using.
If your new employer hasn't received that information before they run payroll, they may have to use a temporary tax code instead.
We'll look at P45s, P60s and P11Ds in more detail in a future guide.
You have two jobs
Most people only receive one full Personal Allowance.
HMRC therefore has to decide which employer should apply it.
Until that happens, one employer may use a temporary code.
This can make your payslip look surprising, even though the system is working as intended.
You're returning to work
If you've had a long career break, lived abroad, or stopped working for a period, HMRC may need time to rebuild your PAYE record before your permanent tax code is applied.
Emergency tax code does not always mean you've paid too much tax
This is one of the biggest misconceptions about PAYE.
Many websites suggest that an emergency tax code automatically means you've overpaid tax. That's not quite true.
An emergency tax code simply changes how PAYE calculates your tax until HMRC has the information it needs. Depending on your circumstances, you could temporarily:
- pay too much tax
- pay too little tax
- pay roughly the correct amount
That said, overpayments are common when someone starts a new job after already working elsewhere during the same tax year. Until HMRC updates your record, payroll may not know how much tax you've already paid.
If you've paid too much, HMRC will usually correct this once your records have been updated.
Your NI number and your tax code are different things
People often mix these up because both appear when you start a job. They do completely different jobs.
| Item | What it identifies |
|---|---|
| National Insurance number | Your National Insurance contribution record and identity within the NI system |
| Tax code | How PAYE should calculate Income Tax from your pay |
| Payroll number | Your employer's internal payroll reference for you |
| UTR (Unique Taxpayer Reference) | Your record for Self Assessment, if you need one |
Your employer normally needs your National Insurance number. HMRC uses your tax code to tell payroll how Income Tax should be calculated.
The two are connected to your employment record, but they are not interchangeable.
How can you tell if you're on an emergency tax code?
The easiest place to check is your payslip. Your tax code may contain letters such as:
- W1
- M1
- X
It usually means PAYE is being calculated on a non-cumulative basis. Instead of looking at your earnings and tax for the whole tax year so far, payroll calculates tax using only the current week's or month's pay.
Some payroll systems use the word NONCUM instead. It means the same thing.
The numbers at the beginning of the tax code can change from year to year as tax allowances change. The important part is usually the W1, M1, X or NONCUM.
For example, you might see:
- 1257L W1
- 1257L M1
- 1257L X
These examples are common, but the numeric part of your tax code can change if tax allowances change in future tax years.
Does this mean payroll made a mistake?
Usually, no.
Employers must follow the tax code they receive from HMRC or the rules that apply when they do not yet have enough information. Payroll staff generally cannot decide to "give you a better tax code" because you ask them to.
If they knowingly use the wrong tax code, they risk calculating PAYE incorrectly. That's why the solution is normally to make sure HMRC has the correct information, rather than asking payroll to override it.
What should you do if your tax code looks wrong?
In many cases, the first step is simple: do not panic after one payslip.
Payroll may have to process your salary before HMRC has sent your employer an updated tax code. If that happens, a temporary code may be used for the first pay period and corrected later.
It is still worth checking that nobody is missing important information.
Step 1: Check whether your employer has the right information
Start with the paperwork you gave your employer. Ask yourself:
- Did you give your employer your P45 from your previous job?
- If you didn't have a P45, did you complete a Starter Checklist?
- Is your name, date of birth and National Insurance number correct in your employer's records?
A temporary tax code can appear simply because one piece of information was not available when payroll processed your first salary.
If you recently changed jobs, check that your previous employer has issued your P45. Your new employer may be able to use it to work out your pay and tax correctly while HMRC updates its records.
Step 2: Check what HMRC has on record
You can check your current tax code through your Personal Tax Account or the HMRC app. This should show information such as:
- your current tax code
- the employers HMRC has linked to you
- your estimated income
- recent changes to your tax code
Look for anything that is clearly out of date. For example, HMRC may still show an old job as active, may have the wrong estimated income, or may have allocated your Personal Allowance to the wrong employer.
If HMRC has already issued the correct code but your payslip still shows the old one, your employer may simply not have applied the update yet. Payroll should normally use the new code after receiving it through the PAYE system.
Step 3: Contact HMRC if the record is wrong
Contact HMRC if the information in your tax account is incomplete or clearly incorrect. Common problems include:
- an old job still being treated as your main employment
- HMRC showing two jobs when you now have only one
- an income estimate that is much too high or too low
- your Personal Allowance being assigned to the wrong job
Once HMRC corrects the record, it can issue a revised tax code to your employer. You normally do not need to calculate the tax yourself, and payroll cannot simply choose a different code because you ask them to.
How long does it take to fix an emergency tax code?
There is no single timetable because it depends on what information is missing, when HMRC updates the record and when your employer next runs payroll.
A straightforward case may be corrected on the next payslip. More complicated cases can take longer, especially if you have more than one job, have changed employers several times during the tax year, or have recently returned to the UK.
The useful thing to check is whether the situation is moving forward. Has HMRC updated the code? Has payroll received it? If several pay periods pass with no change, it is worth following up rather than continuing to wait.
The important thing to remember is that a temporary tax code is exactly that: temporary.
Will you get your money back if you paid too much tax?
Usually, yes.
If too much Income Tax has been deducted through PAYE, HMRC normally adjusts this automatically once your correct tax code is applied.
There are two common ways this happens.
Your next payslip is higher
Usually, yes.
If too much Income Tax has been deducted and HMRC issues a new cumulative tax code, PAYE can recalculate your tax for the year so far. Any overpayment may then be refunded through your salary.
The refund may appear on a later payslip
You may not receive a separate payment. Instead, a later payslip may show less tax than usual, a tax refund, or a noticeably higher take-home amount.
This does not happen in exactly the same way in every case. A non-cumulative code only looks at the current pay period, so payroll may need a cumulative code before it can correct an earlier overpayment through your wages.
HMRC may refund you later
If the overpayment is not corrected through payroll, HMRC may review your tax after the end of the tax year. You may then receive a P800 tax calculation explaining whether you paid too much or too little.
If a refund is due, HMRC will tell you how it will be paid or whether you need to claim it.
What if you've paid too little tax?
An unexpected tax code can also result in too little tax being deducted. This is less comforting when your payslip looks unusually generous, but it is still something to check.
HMRC may correct the underpayment by changing your tax code so that the remaining amount is collected through future wages. In some cases, HMRC may contact you separately about how the tax will be recovered.
This is why it is sensible to investigate an unfamiliar code even when your take-home pay is higher than expected.
Check the rest of your payslip too
A tax code is only one part of a payslip. While you are checking it, look at the other deductions as well, including:
- pension contributions
- National Insurance
- student loan or postgraduate loan deductions
- salary sacrifice
- other workplace deductions
A pension deduction on your first payslip may be completely normal if you have joined, or been automatically enrolled into, a workplace pension.
If you are not sure what the deduction means, read UK Pensions, Explained Like a Normal Person.
Keep the paperwork
Once your tax code has been corrected, don't throw everything away.
Keep copies of:
- your first payslip
- later corrected payslips
- your P45 (if you received one)
- any tax code notices from HMRC
- any letters or messages confirming changes
Problems are rare, but if something doesn't add up later, having the documents makes it much easier to understand what happened.
If you already keep your important paperwork digitally, save these documents alongside your employment records.
Our guide to Building a Digital Filing System That You'll Actually Use shows one simple way to organise them without creating dozens of complicated folders.
Can you avoid an emergency tax code?
Not always.
Sometimes it's simply part of the normal process of starting a new job.
However, you can reduce the chances by:
- giving your new employer your P45 as soon as possible
- completing a Starter Checklist accurately if you don't have a P45
- making sure HMRC knows about changes to your employment
- checking your Personal Tax Account if something doesn't look right
- keeping your employment documents organised
Even if you do everything correctly, there can still be a short delay while information moves between employers and HMRC.
That doesn't necessarily mean anyone has made a mistake. The important thing is to check the information, keep the evidence and follow up if the code does not change.
Tax codes you might see on your payslip
An emergency tax code is not the only unfamiliar code you may see on a payslip. Different letters and numbers tell payroll how to calculate Income Tax for that particular job.
Here is a quick overview of some common codes:
| Tax code | What it generally means |
|---|---|
| A code ending in L | You are entitled to the standard tax-free Personal Allowance, although the number may be adjusted for your circumstances. |
| W1, M1, X or NONCUM | Tax is being calculated using only the current pay period. These endings identify an emergency tax code. |
| BR | All income from this job is taxed at the basic rate. It is often used for a second job when your Personal Allowance is applied elsewhere. |
| D0 | All income from this job is taxed at the higher rate. |
| D1 | All income from this job is taxed at the additional rate. |
| 0T | No Personal Allowance is applied to this job. This may happen if HMRC does not have enough information or your allowance is already being used elsewhere. |
| NT | No Income Tax is deducted from this employment. |
| A code beginning with K | HMRC is collecting tax on income or deductions that are greater than your available Personal Allowance, such as tax owed from an earlier year or certain taxable benefits. |
Scottish and Welsh tax codes can include different prefixes and rates, so the exact meaning may depend on where you live.
None of these codes automatically means payroll has made a mistake. Your code depends on your income, benefits, other jobs and wider tax position. If you do not understand why a particular code has been used, check your HMRC account before assuming it is wrong.
Frequently asked questions
Can I work while I'm on an emergency tax code?
Yes. An emergency tax code only affects how PAYE calculates your Income Tax. It does not affect your employment contract, immigration status or right to work.
Does an emergency tax code affect my National Insurance?
No. Income Tax and National Insurance are calculated under separate rules. Your PAYE tax code affects Income Tax, while your employer uses your National Insurance category and earnings to calculate National Insurance contributions. :contentReference[oaicite:1]
Will my employer know that my tax code has changed?
HMRC normally sends the new code directly to your employer. Payroll should update your record as soon as possible and, where the notice arrives in time, before the next payment is processed.
You usually do not need to give payroll a paper copy of your coding notice. If your new code has not appeared after the expected payroll cycles, ask whether they have received the latest notice from HMRC. :contentReference[oaicite:2]
Should I ask payroll to change my tax code?
You can ask payroll to check which code they are using, but they cannot simply choose another one because it seems fairer. They must normally follow the code sent by HMRC or the official starter rules that apply when no code is available.
If HMRC holds incorrect information, HMRC usually needs to correct it and issue a new code.
Can I have an emergency tax code if I have two jobs?
Yes. Having more than one job can make unexpected tax codes more likely, particularly while HMRC works out where your Personal Allowance should be used.
However, codes such as BR, D0 or D1 are not automatically emergency codes. They are rate-based codes and may be entirely correct for a second job. :contentReference[oaicite:3]
What if my tax code still hasn't changed?
Check your HMRC account first. If the employment details, estimated income or tax code shown there are wrong, update the information or contact HMRC.
If HMRC shows the correct code but your employer is still using the old one, ask payroll whether they have received the latest coding notice. HMRC says that, after a code is changed, it should generally appear on the next or following monthly payslip, or by the third weekly payslip. :contentReference[oaicite:4]
Can I get an emergency tax code every time I change jobs?
Not necessarily. Many people change jobs without ever seeing one because their new employer receives enough information in time.
A temporary code may still be used if your P45 is unavailable, your Starter Checklist is incomplete, or HMRC has not yet sent the correct code before your first payroll is processed.
A simple way to think about it
An emergency tax code is usually temporary. W1, M1, X and NONCUM are the parts that identify it. It does not automatically mean you have overpaid tax. Check HMRC's records and keep your payslips until the issue is resolved.
Related guides
If you're just starting work in the UK, these guides may also help:
- Your First Adult Documents Pack in the UK
- UK Pensions, Explained Like a Normal Person
- Building a Digital Filing System That You'll Actually Use
- A Minimal System for Remembering Annual Tasks
Final note
An unfamiliar code on your first payslip can look alarming, particularly when you are new to the UK or returning to work after a break. In most cases, it means the PAYE system is working with incomplete information rather than that you have done something wrong.
Check that your employer has the documents they need, compare the code on your payslip with the one held by HMRC, and follow up if it does not change within the expected payroll cycles.
Keep the first payslip, the corrected payslip and any HMRC notices together. Once the records have been updated, PAYE can usually make the necessary adjustment automatically.