What is emergency tax and how do I get it refunded?

In plain English

Under normal PAYE, your personal allowance and tax bands are spread evenly across the year. Each pay run looks at your cumulative earnings and tax-to-date so any over- or under-payment is corrected automatically. Emergency tax replaces this with a per-period calculation: the system pretends each pay period is the first of the year and applies one twelfth (or one fifty-second) of the allowance, regardless of what you have already earned.

This basis appears most often when starting a new job without a P45, when taking the first taxable pension drawdown, or when HMRC has incomplete information. The code may still look familiar - for example 1257L W1 - but the W1, M1 or X marker is the signal that the calculation is non-cumulative.

For steady monthly pay, emergency tax can produce results close to the correct amount. Where it tends to go wrong is with irregular pay, joining mid-year, large lump sums (such as a flexible pension withdrawal), or back-pay. In those cases the system may over- or under-collect tax until reconciled by HMRC.

HMRC generally moves you onto a cumulative code as soon as they have the data, often within one or two pay periods. Once the cumulative code is applied, the next payroll typically refunds any overpayment automatically. For pension flexible withdrawals, a separate claim form (P55, P53Z or P50Z) may be needed.

It is worth distinguishing emergency tax from a wrong tax code. A wrong code applies the incorrect allowance permanently; an emergency code applies the correct allowance but on a non-cumulative basis. Both can produce an unexpected take-home figure, and the symptoms on the payslip can look similar, but the underlying cause is different. The W1, M1 or X marker is the key signal that the basis - rather than the code itself - is the problem. This does not prove the employer or HMRC has made an error; it appears consistent with the standard PAYE response when starter information is incomplete.

Based on HMRC guidance for 2026/27, the personal allowance is £12,570, the basic rate band runs to £50,270, the higher rate band runs to £125,140, and the additional rate of 45% applies above. Under emergency code 1257L on a Month 1 basis, the system applies £1,047.50 of allowance per month and taxes the first £3,141.67 above that at 20%. If your monthly pay sits comfortably within these bands and is broadly steady, the emergency calculation may produce a result that looks almost identical to the cumulative outcome. The mismatch grows when pay is irregular, when you join part-way through the year, or when bonuses push you across a threshold.

What triggers emergency tax

• Starting a new job without providing a P45 from the previous one.
• Starting your first job and HMRC not yet having an allowance allocation in place.
• Taking a flexible pension lump sum where the provider has no current code.
• Returning to work after a career break with no recent PAYE record.
• Switching from self-employment into PAYE mid-year.

Worked example (2026/27 figures)

Sam starts a new job on 1 August 2026 earning £42,000 a year (£3,500/month) and has no P45. The employer applies code 1257L on a Month 1 basis. Each month, the calculation gives a tax-free amount of £12,570 ÷ 12 ≈ £1,047.50, leaving £2,452.50 taxed at 20% = £490.50.

On a cumulative basis, however, Sam would be entitled to the unused allowance from April through July (4 × £1,047.50 = £4,190) on top of the August allowance. Once HMRC issues a cumulative 1257L code, the next payroll appears consistent with refunding the over-collected tax (broadly 4 × £1,047.50 × 20% = £838) through reduced deductions that month. This does not prove an error in the original payslip - it is how PAYE catches up.

Consider a second scenario. Maya, age 58, takes a one-off £20,000 flexible drawdown from a personal pension in June 2026 and has no other income that year. The provider is required to apply an emergency tax code on a Month 1 basis. The calculation treats £20,000 as if it were one twelfth of an annual pattern, so it allocates roughly £1,047.50 of allowance and applies basic, higher and even additional rate bands within the period. The deduction may be far higher than the eventual liability, since across the full year Maya's actual liability would be calculated against the full £12,570 allowance and the £50,270 basic rate band. A P55 reclaim form is the standard route to recover any overpayment in circumstances like this; based on HMRC guidance, the refund typically arrives within a few weeks of submission.

A third scenario: Tom, returning to work after six months abroad, starts a part-time role in September on £18,000 a year (£1,500/month). Under emergency 1257L Month 1, monthly tax is (£1,500 − £1,047.50) × 20% = £90.50. On a cumulative basis, he would be entitled to all the unused allowance from April to August. When HMRC issues a cumulative code in October, the payslip may show negative tax for that month - that is, a refund - until the year-to-date position rebalances. NI of 8% on earnings above £12,570 (or £1,047.50/month) continues to apply per period regardless of basis.

Common mistakes people make

• Assuming the code is wrong because the marker (W1/M1/X) looks unfamiliar.
• Asking payroll to change the code - they cannot, only HMRC can issue a new code.
• Missing P55/P53Z/P50Z claims after pension flexible drawdown.
• Not registering for a Personal Tax Account, which often speeds up code corrections.
• Believing the refund will arrive separately from HMRC; in PAYE it normally appears in payroll.
• Submitting a starter declaration option C (multiple jobs) when option A or B would be appropriate, locking in BR or 0T unnecessarily.
• Treating an emergency code as something to argue with payroll about; the fix usually sits with HMRC and the Personal Tax Account.
• Cancelling salary sacrifice or pension contributions to "fix" the figure - these usually have no effect on emergency tax and may create separate problems.
• Comparing the gross-to-net result against an online calculator without setting the calculator to a non-cumulative basis, which appears consistent with overestimating the apparent overpayment.

When this might apply to you

1. You started work this month and the payslip shows W1 or M1.
2. You took a flexi-access pension lump sum and noticed unusually high tax.
3. You moved from a contract role into permanent PAYE without a P45.
4. You returned to the UK workforce after time abroad.
5. You completed a starter declaration choosing option C (multiple jobs).
6. You finished a fixed-term contract, had a gap, and started a new role without your previous P45 to hand.
7. You moved from agency work paid through PAYE into permanent employment, and the agency has not yet issued a P45.
8. You retired partially - taking some pension while continuing in part-time work - and one of the income sources has triggered a non-cumulative basis.

What to do if this applies to you

1. Confirm the marker - look for W1, M1 or X on your payslip.
2. Provide a recent P45 to your employer if you have one.
3. If you do not have a P45, complete a starter declaration accurately so HMRC has the right information to issue a code.
4. Sign in to your HMRC Personal Tax Account and verify your employment record is correct, including end dates for any previous job.
5. Check the National Insurance record shows the new employer; missing employer details are a common reason for delay.
6. Wait one to two pay cycles - most cases resolve automatically once HMRC issues a cumulative code.
7. If you took a pension lump sum and need an in-year refund, complete the relevant HMRC reclaim form (P55, P53Z or P50Z) rather than waiting for year-end reconciliation.
8. Keep a copy of every payslip from the period; year-end P60 figures should reconcile to the cumulative position.
9. Use our payslip check to confirm the figures appear consistent with the rates and thresholds for 2026/27.

When to contact HMRC, payroll, or a professional

Contact payroll to confirm what code they hold and whether they have received an updated notice from HMRC. Contact HMRC if more than two pay periods have passed without a cumulative code or if your employment record is wrong. Consider a tax professional if the issue arose from a pension drawdown, complex multiple-employment situation, or a large untaxed amount.

Frequently asked questions

Related guides and tools

• UK tax codes explained
• Wrong tax code checklist
• PAYE cumulative vs non-cumulative
• Tax refund estimator
• Take-home pay calculator
• Run a free payslip check

Educational content only; not regulated tax advice.