How to Claim an Emergency Tax Refund from HMRC (2026)

What Is an Emergency Tax Code?

When you start a new job and do not have your P45 from your previous employer, HMRC does not have complete information about how much you have already earned and been taxed in the current tax year. Rather than delay your pay while they obtain this information, your new employer applies an emergency tax code.

Emergency tax codes are also applied when someone takes pension payments for the first time (e.g., starting to draw from a personal pension), when HMRC's systems cannot process a code change in time, or in certain circumstances when employment details are incomplete.

The practical consequence is that you are often taxed more heavily than you should be — sometimes significantly so.

The Main Emergency Tax Codes

1257L W1 or 1257L M1

This is the most common emergency code. The "W1" means "Week 1 basis" and "M1" means "Month 1 basis" — both refer to the same non-cumulative approach, just applied depending on whether you are paid weekly or monthly.

Under a W1/M1 basis, your employer applies only one week's (or one month's) worth of your Personal Allowance to each pay period, rather than looking at what you have earned cumulatively since April. This means:

• If you had a period of no income earlier in the year (e.g., you were unemployed), that unused allowance is not carried forward
• If your first full month of income at the new job is a high-earning month, all the income above the monthly allowance (£1,047.50 per month in 2026/27) will be taxed at 20% even if your annual income is below the higher rate band

In many cases, this causes only a moderate overpayment. But if you started a new job late in the tax year with a previous period of no income, the cumulative under-utilisation of your allowance can lead to a significant refund entitlement.

BR (Basic Rate)

A BR tax code means all your income in that employment is taxed at 20% with no Personal Allowance applied. This is one of the most overtaxing codes possible for a basic rate taxpayer.

BR codes are commonly applied to a second job or second pension, on the assumption that the Personal Allowance is already fully used by the main job. However, they can also be applied as an emergency code when HMRC has no information at all about your circumstances.

Example of overpayment: Monthly salary of £2,800. With a correct 1257L code, tax would be approximately £287 per month. Under a BR code (no allowance), tax would be £560 per month — an overpayment of £273 per month, or £3,276 over a full year.

0T

The 0T code means zero allowance and applies the correct tax bands (20%, 40%, 45%) to all income. It is typically used when your employer has no information from you at all — you did not fill in a starter checklist and there is no P45. It is less common than BR as an emergency code but results in significant overpayments for basic rate taxpayers.

D0 and D1

D0 means all income is taxed at 40% (higher rate) and D1 means 45% (additional rate). These are used for second employments where HMRC believes you are already a higher or additional rate taxpayer, but can occasionally appear as emergency codes in error.

How Much Could You Have Overpaid?

The amount of overpayment depends on your code, your salary, and how many months you were on the emergency code before it was corrected. The table below gives approximate monthly overpayment figures for a 1257L W1 code applied to someone who was previously unemployed (i.e., they had many months of unused allowance):

The most reliable way to know your overpayment is to use your Personal Tax Account or speak to HMRC with your P45, payslips, and P60 to hand.

How to Claim Your Emergency Tax Refund

There are three routes to reclaiming overpaid emergency tax:

Route 1: Through Your Employer (In-Year)

The fastest resolution is to get the correct tax code applied while you are still employed. To do this:

1. Give your P45 to your new employer — this is the key document. Your old employer should have given it to you when you left. Your new employer's payroll team can use it to notify HMRC of your previous earnings and tax paid.
2. Complete a new starter checklist (previously P46) — if you do not have a P45, this form helps HMRC determine the correct code
3. Confirm the correct code is applied — check your next payslip after the code change is processed

Once HMRC updates your code to a cumulative one (removing the W1/M1 suffix), your employer's payroll software will automatically recalculate your tax for the full year and refund any overpayment in your next pay packet. This is often the fastest route — you may see the refund within a single pay period.

Route 2: Online via Personal Tax Account

If you no longer work for the employer who applied the emergency code, or if several months have passed, you can claim via HMRC's online service:

1. Go to gov.uk/personal-tax-account and sign in with your Government Gateway credentials (or create an account)
2. Navigate to the tax section and review your tax position for the current year
3. If HMRC's records show an overpayment, you can request a refund directly online
4. Provide your bank details for payment

Online refunds typically arrive within 5 working days — significantly faster than waiting for a cheque.

Route 3: Contact HMRC Directly

If you cannot use the online service or prefer to speak to someone, call the income tax helpline on 0300 200 3300. Lines are open Monday to Friday, 8am to 6pm. Have ready:

• Your National Insurance number
• Your P45 or P60
• Your payslips showing the emergency code and tax deducted
• Your employer's PAYE reference (on your payslip or P60)

HMRC can issue a refund by cheque or arrange a bank transfer. Cheques sent by post take longer — typically 6 to 12 weeks from the point HMRC processes the claim.

Route 4: Wait for the P800 Annual Reconciliation

After each tax year ends, HMRC runs an automatic reconciliation of all PAYE records. If you overpaid tax at any point during the year — including via an emergency code — HMRC will send you a P800 tax calculation in the summer (typically July to November) showing the amount owed.

If the P800 shows a refund is due, you can:

• Claim online (5 working days to receive payment)
• Do nothing and HMRC will send a cheque (up to 12 weeks)

This is the passive route — but it works. The downside is you may be waiting several months after the tax year ends before the refund arrives.

What If You Have Left the UK or Left Employment Mid-Year?

If you have left your job and will not be working again before 5 April, you may be able to claim a refund for the remainder of the tax year using form P50Z (ceased employment, no other income) available from HMRC's website. This accelerates the process rather than waiting for the end-of-year P800.

Tips to Avoid Emergency Tax in Future

• Always obtain your P45 when leaving a job and give it to your new employer on day one
• If you lose your P45, contact your old employer to issue a duplicate or ask them to update HMRC's RTI records directly
• Complete the new starter checklist carefully and honestly — ticking the wrong box (e.g., saying this is your only job when it is not) can result in an incorrect code
• Check your payslip after your first or second pay at a new job to confirm the correct tax code is being used
• If you are drawing a pension for the first time, be aware that pension providers often apply emergency codes to the first payment

Summary

Emergency tax codes are a common source of unexpected overpayments, particularly for people changing jobs, starting pensions, or returning to work after a gap. The solution is usually straightforward: provide your P45 to your employer, confirm the correct cumulative code is applied, and the overpayment will be refunded automatically through payroll. If you have already left the job or if the tax year has ended, claiming via your Personal Tax Account online is the quickest route, with refunds arriving within 5 working days. Do not wait — if you spot an emergency code on your payslip, act quickly to minimise the overpayment.