If you've started a new job and noticed much more tax being deducted than expected, you're probably on an emergency tax code. Emergency tax can mean paying hundreds of pounds extra per month until it's corrected. This comprehensive guide explains what emergency tax codes are, why they happen, how much you're overpaying, and exactly how to fix them.
What Is Emergency Tax?
Emergency tax is when HMRC temporarily applies a tax code (usually 1257L W1/M1, BR, or 0T) because they don't have complete information about your tax circumstances. It typically results in you paying significantly more tax than necessary - money you'll need to reclaim later.
Emergency tax happens because the UK tax system operates on a cumulative basis throughout the tax year (6 April to 5 April). When HMRC doesn't have your full employment history for the current tax year, they can't calculate your cumulative position, so they tax you as if this is your only income or apply non-cumulative codes.
The good news: Emergency tax is always temporary and you will get the money back, either through adjusted future pay or a refund from HMRC.
Use our Tax Code Calculator to check if you're on emergency tax and see exactly how much you're overpaying each month.
Common Emergency Tax Codes Explained
1257L W1 or M1
This is the most common emergency tax code for 2025/26. It gives you the standard Personal Allowance of £12,570, but applies it on a non-cumulative basis:
- W1 means "Week 1" - your tax is calculated only for that week
- M1 means "Month 1" - your tax is calculated only for that month
The problem: Without cumulative tax relief, you lose months of unused Personal Allowance if you start work mid-year.
Example: If you start a new job in January earning £30,000: - With 1257L M1, you get 1/12th of your Personal Allowance each month (£1,047.50) - With correct 1257L code, you'd get your full unused allowance from April-December (9 months = £9,427.50) - You overpay tax on £8,380 of income = £1,676 overpaid
BR - Basic Rate
BR means all your income is taxed at 20% with no Personal Allowance at all.
When it's used:
- New job without a P45
- Second job (often correct for second jobs)
- Pension income
The problem: You're taxed from £1, not from £12,570.
Example: £35,000 salary on BR code:
- Tax paid: £7,000 (20% of everything)
- Correct tax: £4,486 (20% of £35,000 - £12,570)
- Monthly overpayment: £209.50
0T - No Allowances
0T means you get no Personal Allowance but tax is applied at the correct rates (20%, 40%, 45%) based on income bands.
When it's used:
- You've used all your Personal Allowance elsewhere
- HMRC needs more information
- Your income exceeds £125,140 (Personal Allowance tapers to zero)
The difference from BR: 0T applies progressive rates, so if you earn £60,000, you pay 20% on first £50,270 and 40% on the rest. BR would only charge 20% on everything.
D0 (Higher Rate) and D1 (Additional Rate)
- D0: All income taxed at 40%
- D1: All income taxed at 45%
When they're used:
- Usually for second jobs when you're a higher/additional rate taxpayer
- HMRC expects all income from this source falls in the higher/additional rate band
Learn more about how UK Income Tax rates and bands work.
Why You're On Emergency Tax
Starting a New Job Without a P45
The most common reason. Your P45 from your previous employer tells your new employer:
- How much you've earned this tax year
- How much tax you've already paid
- Your correct tax code
Without it, your new employer must use an emergency code until HMRC provides the correct one.
Multiple Jobs
If you're working two jobs simultaneously, your second job will usually be taxed at BR or D0 because your Personal Allowance can only be used against one employment.
This is often correct - check with our Multiple Jobs Calculator to see your proper tax position.
Benefits and Expenses
If you receive company benefits (company car, private medical insurance) or have expenses through your employment, HMRC might put you on an emergency code while they calculate your adjusted tax code.
Tax Year Changeover
At the start of the tax year (6 April), HMRC issues new tax codes. If they don't have updated information about your circumstances, you might start on an emergency code.
Self-Employment to Employment
If you were previously self-employed and are now employed, HMRC might not have updated their records, resulting in an emergency code.
Student Loan Status Changes
Changes to your student loan status can trigger tax code updates. During the transition, you might be put on emergency tax.
How Much Are You Overpaying?
The overpayment depends on your salary and which emergency code you're on:
| Salary | BR Code (Monthly) | 1257L M1 Starting Jan (Total) |
|---|---|---|
| £25,000 | £166.67 overpaid | £1,046 overpaid |
| £30,000 | £209.50 overpaid | £1,256 overpaid |
| £40,000 | £295.17 overpaid | £1,676 overpaid |
| £50,000 | £380.83 overpaid | £2,096 overpaid |
| £60,000 | £531.67 overpaid | £2,600 overpaid |
These figures show why emergency tax is such a problem - especially for higher earners or those starting mid-year.
Calculate your exact overpayment with our Take Home Pay Calculator by comparing your current deductions to the correct ones.
How to Fix Emergency Tax: Step-by-Step
Step 1: Provide Your P45 (If You Have One)
If you have a P45 from your previous job:
- Give it to your new employer immediately - ideally on or before your first day
- Your employer will use the information to set your correct tax code
- Correction usually happens within 1-2 payrolls
- Any overpaid tax will be refunded through your salary
Don't have your P45? Your previous employer must provide it within 14 days of you leaving. If they won't, contact HMRC.
Step 2: Contact HMRC Directly
If you don't have a P45 or it's taking too long:
Online (Fastest):
- Go to gov.uk/personal-tax-account
- Log in with Government Gateway
- Select "Update employment details"
- Add your new employment information
- HMRC will issue a new tax code within 3-5 working days
By Phone:
- Call HMRC on 0300 200 3300
- Have your National Insurance number ready
- Provide details of previous and current employment
- HMRC will update your code and send confirmation to your employer
What to tell HMRC:
- Your new employer's name and PAYE reference
- Your start date
- Details of previous employment (dates, income)
- Whether you have other sources of income
Step 3: Check Your Payslip
Once HMRC issues your new code:
- Your employer receives it electronically within 3 working days
- Applied from next payroll - watch your next payslip
- Verify the tax code - it should no longer have W1, M1, BR, or 0T
- Verify deductions - use our Tax Code Calculator to check
Step 4: Get Your Refund
Automatic refund (most common):
- Your new correct code will be "cumulative"
- HMRC calculates how much you overpaid
- The refund comes through your salary over remaining months
- You'll see negative tax deductions or higher net pay
Example: If you overpaid £1,200 and there are 6 months left in the tax year, you'll get an extra £200 per month.
End-of-year refund: If you're still owed money after 5 April:
- P800 tax calculation - HMRC sends this automatically if they owe you
- Claim form P50 - use if you've stopped working
- Claim form P45 - use when you leave a job
Refunds arrive within 5 weeks of claiming.
Special Cases and Scenarios
Second Jobs
If it's genuinely a second job and you're earning enough that your Personal Allowance is used by your first job, BR or D0 codes are correct.
Check if it's right:
- Add both salaries together
- See if combined income exceeds £12,570 (basic allowance) or £50,270 (higher rate threshold)
- If yes, the emergency code might be correct
Use our Multiple Jobs Calculator to verify.
Pension Income
Private pensions are often initially taxed at BR until HMRC confirms your total income from all sources.
If you have pension income alongside employment, make sure HMRC knows about all sources so they can split your allowances correctly.
Leaving Employment Mid-Year
If you leave a job and don't start another, you can claim back overpaid tax immediately using:
- P50 form if you're not working
- P45 form if you're starting a new job
Don't wait until April - you might be owed hundreds or thousands.
Self-Employed to Employed
Former self-employed people often face emergency tax because HMRC's records show no PAYE employment history.
Contact HMRC proactively when you start employed work after self-employment to avoid this.
Preventing Emergency Tax
For Future Job Changes
- Request P45 immediately when leaving a job
- Provide P45 to new employer on or before first day
- Keep payslips from previous employment as backup
- Register for Personal Tax Account to update HMRC directly online
Keep HMRC Informed
Tell HMRC about changes:
- New jobs or leaving employment
- Change of address
- Multiple employments starting/ending
- Additional income sources
The more HMRC knows, the less likely you'll face emergency tax.
Start-of-Tax-Year Checks
Every April, check:
- Your tax code for the new tax year
- That all employments are correctly listed
- Your Personal Allowance hasn't been unexpectedly reduced
Access this through your Personal Tax Account at gov.uk.
Emergency Tax and Student Loans
If you have a student loan, emergency tax doesn't directly affect your loan repayments - they're calculated separately.
However, BR codes can affect how your student loan plan is identified, potentially putting you on the wrong repayment threshold temporarily.
Ensure your new employer has your correct student loan plan (Plan 1, 2, 4, 5, or Postgraduate) from your P45.
Emergency Tax and National Insurance
National Insurance is always calculated correctly on your actual earnings in each pay period - it's not affected by emergency tax codes.
You won't overpay NI due to emergency tax, only Income Tax.
When Emergency Tax Might Be Correct
Not all emergency-looking codes are wrong:
BR is correct for:
- Second jobs where your allowance is used on job 1
- Pension income when you have employment using your allowance
- Benefits in kind exceeding your remaining allowance
0T is correct for:
- Earners over £125,140 (no Personal Allowance)
- People who have used their allowance elsewhere
D0/D1 is correct for:
- Second jobs for higher/additional rate taxpayers
- Income fully falling in higher/additional rate bands
Always check with our calculators to verify whether your code should be corrected or if it's actually right for your circumstances.
Tax Code Changes: What to Expect
Once emergency tax is corrected:
Week 1: HMRC updates their system Week 2: Your employer receives the new code electronically Week 3: New code applied to your next payroll Week 4+: Refund starts coming through your salary
Total timeline: 2-4 weeks from contacting HMRC to receiving your refund.
If it takes longer than 6 weeks, contact HMRC again.
Related Guides
- Understand all UK Tax Codes in detail
- Learn how PAYE works
- Check your Tax Code is correct
- Calculate your proper Take Home Pay
- Read about Income Tax rates and bands
Frequently Asked Questions
How long does emergency tax last? Emergency tax should be corrected within 2-4 weeks once you've provided your P45 or contacted HMRC directly. Refunds typically come through your next payslip after the correction, spread over the remaining months of the tax year.
Will I automatically get my money back? Yes, once your correct tax code is applied, HMRC calculates the overpayment and refunds it through your salary automatically. If you're still owed money at the end of the tax year (5 April), HMRC will send a P800 tax calculation or you can claim using a P50/P45 form.
Can I be on emergency tax in a second job? Yes, second jobs are frequently taxed at BR (20%) or D0 (40%) rates because your Personal Allowance is usually allocated to your primary employment. However, this is often the correct tax treatment. Use our Multiple Jobs Calculator to verify.
What's the difference between BR and 0T codes? BR taxes all your income at a flat 20% basic rate with no Personal Allowance. 0T also removes your Personal Allowance but applies the correct progressive tax bands (20%, 40%, 45%) based on your income level, so higher earners pay higher rates.
Do I need a P45 to avoid emergency tax? No - you can avoid emergency tax by contacting HMRC directly through your Personal Tax Account online or by phone (0300 200 3300). However, providing your P45 to your new employer is the fastest and easiest way to get the correct tax code immediately.