UK Emergency Tax Code: Why You Got One

Emergency tax codes appear when an employer cannot apply the standard cumulative PAYE method for a particular employee. Common triggers are a new job without a P45 from the previous employer, the first drawdown from a pension scheme, returning from abroad, starting a second job, or any situation where year-to-date PAYE data is missing.

The emergency code typically carries the standard allowance (1257L) with a W1 or M1 suffix indicating week one or month one. Each pay period stands alone for the calculation, applying one-twelfth (monthly) or one-fifty-second (weekly) of the allowance. This guide covers why emergency codes happen, how they look on a payslip, and how to switch to a cumulative code.

What an emergency code does to your pay

An emergency code applies the Personal Allowance to each pay period independently. A monthly-paid employee on 1257L M1 receives GBP 1,047.50 of allowance applied to that month's pay only. Any unused allowance from earlier months does not carry forward; any over-taxation in earlier months is not corrected until a cumulative code is applied.

For an employee with steady monthly pay above the monthly allowance, the emergency code produces the same monthly tax as a cumulative code (since each month uses the same allowance either way). For an employee whose pay varies, the emergency code can over-tax in higher months and under-tax in lower months relative to the cumulative position.

Worked example: a new starter joining in October at GBP 36,000 (GBP 3,000 a month) is placed on 1257L M1. Each month October to March applies allowance GBP 1,047.50, taxable GBP 1,952.50 at 20% = GBP 390.50 tax. Annual tax over 6 months = GBP 2,343. Had a cumulative code applied from joining (with no prior PAYE in the year), the same employee would have received the full GBP 12,570 allowance against the GBP 18,000 earned, taxable GBP 5,430 at 20% = GBP 1,086 tax for the part year. Difference: GBP 1,257 of over-tax across 6 months.

Practical action: this over-tax is recoverable. Once HMRC issues the corrected cumulative code (typically after the first RTI submission lands), the next payroll run applies the year-to-date allowance retroactively and produces a large tax refund line on that month's payslip. The refund comes through in regular pay, not as a separate payment.

Common triggers for an emergency code

The most common trigger is a new job started without a P45 from the previous employer. The starter checklist (the modern replacement for form P46) collects whether the employee has another job and indicates which emergency code applies: 1257L M1 (only job, no P45), BR (second job), 0T M1 (other circumstances).

Pension drawdown first payment is another major trigger. When an employee accesses a pension for the first time, the pension provider often applies an emergency code on the first payment, producing significant over-tax on lump-sum-style withdrawals. HMRC issues a corrected code shortly after, but the first month is typically over-taxed and the over-tax recovered via P50Z, P53Z or P55 forms (depending on the drawdown type) or through PAYE reconciliation in following months.

Returning from abroad to UK employment commonly triggers an emergency code where the employee has no prior UK PAYE record in the year. HMRC reissues a cumulative code once residence is confirmed and the employee's tax position assessed.

Edge case: a code change mid-year that increases the allowance (Marriage Allowance receipt, removal of a benefit in kind) does not normally trigger an emergency code. HMRC issues a cumulative code with the new allowance and the employer applies it from the next pay run, with the cumulative method producing a refund line for any over-tax already paid.

0T code and the no-allowance variant

Code 0T is technically not an emergency code but produces similar effects. It applies no Personal Allowance and uses the full band rates from the first pound of pay (20% on the basic rate band, 40% on the higher band, 45% on the additional rate band). 0T typically appears where HMRC needs to apply deductions through PAYE but cannot allocate the allowance: a redundant employer, a director with multiple income sources, or a temporary fix during a coding investigation.

0T M1 (non-cumulative) is more aggressive than 1257L M1 because no allowance is applied at all. A GBP 3,000 monthly pay would attract GBP 600 of tax (20% on the full GBP 3,000) versus GBP 390 on 1257L M1. For higher earners on 0T, a single pay period can attract 40% on the slice above GBP 3,141.67 (1/12 of GBP 37,700 basic-rate band).

Worked example: a director receives a GBP 50,000 dividend-equivalent payment through payroll on 0T M1. Tax: GBP 3,141.67 at 20% = GBP 628, GBP 6,239.17 at 40% = GBP 2,496, GBP 40,619 at 45% = GBP 18,279. Total GBP 21,403, against an annualised position that might be much lower. The over-tax is recovered in the year-end reconciliation or by code correction during the year.

Practical action: code 0T appearing on a payslip should trigger immediate PTA review. In most cases the correct allowance can be allocated by updating HMRC through the PTA, and a corrected code issued within a few days.

How to switch to a cumulative code

The fastest route is the Personal Tax Account. Once the new employer's first RTI submission lands with HMRC (typically within a week of the first pay date), HMRC normally issues a cumulative code automatically. Where it does not, the PTA's 'Check your tax code' section provides a route to ask HMRC to review.

The HMRC income tax helpline (0300 200 3300) handles cases where the PTA cannot resolve. Wait times are typically 10 to 20 minutes outside peak. Having the new employer's PAYE reference (visible on the payslip) and the employee's NI number to hand speeds the call.

Where a P45 from the previous employer arrives after the starter checklist has been processed, the new employer can issue the P45 to HMRC and apply the year-to-date tax and pay totals to the cumulative method. This is the cleanest route to the correct position.

Edge case: a P45 that arrives after the employee's first pay run may not be immediately processable by the new employer's payroll system. The PTA route allows HMRC to validate the year-to-date position directly and issue the corrected code without dependency on the previous employer's paperwork.

Reclaiming over-paid emergency tax

Over-tax paid under an emergency code is normally recovered automatically when HMRC issues the cumulative code. The next pay run applies year-to-date allowance and band capacity and produces a refund through the PAYE deduction line. No separate claim is needed.

Where the employment ended before the cumulative code was issued (a short-term contract finished in the same tax year), the over-tax is recovered through form P50 (if no further employment in the year) or through the Self-Assessment return (if SA registered). The P50 route normally pays within four weeks of submission.

For pension drawdown emergency tax, the specific forms are P53Z (full withdrawal of a small pot under the small pots rule), P55 (partial withdrawal of a flexible pension), and P50Z (small pension fully withdrawn and no further income). Each form recovers the over-tax within 30 days of HMRC processing.

Practical action: where a one-off pension lump sum is planned and the saver wants to avoid the emergency code shock, taking a small first drawdown (GBP 100 or so) in an earlier month allows HMRC to issue a corrected code before the main withdrawal. The full withdrawal then attracts the correct tax rate from the start.

Frequently asked questions

What does 1257L M1 mean?

1257L is the standard tax code applying the full Personal Allowance of GBP 12,570 in 2026/27. The M1 suffix means Month 1 - the allowance is applied to each month's pay independently rather than cumulatively year-to-date. The result is over-taxation in early months for any employee whose pay started later than the start of the tax year. Once HMRC issues the corrected cumulative 1257L code, the next pay run produces a tax refund through the PAYE line.

Why am I on an emergency tax code in a new job?

Usually because the new employer started the payroll without a P45 from the previous employer. The starter checklist captures the employee's situation and indicates the code to use: 1257L M1 (only job, no P45), BR (second job), 0T M1 (other). The employer applies the emergency code until HMRC issues a cumulative code based on the first RTI submission. The corrected code typically arrives within one to two pay periods.

How long does emergency tax last?

Typically one to two pay periods after the new employer's first RTI submission lands with HMRC. Within around two weeks of joining, HMRC issues a cumulative code based on the year-to-date position. The next pay run applies the cumulative method and produces a refund line for any over-tax. Where the code does not update automatically, the Personal Tax Account is the route to ask HMRC to review.

Will I get my emergency tax back?

Yes. Once HMRC issues the cumulative code, the next pay run applies year-to-date allowance and band capacity and refunds the over-tax through the PAYE deduction line in regular pay. Where employment ends before the cumulative code arrives, the P50 form (no further employment in the year) or the Self-Assessment return recovers the over-tax. For pension drawdowns, P53Z, P55 or P50Z apply depending on the withdrawal type.

What's the difference between 1257L M1 and 0T?

1257L M1 applies the full Personal Allowance month by month. 0T applies no allowance at all and uses the full band rates from the first pound (20% basic, 40% higher, 45% additional). 0T is more aggressive and over-taxes more, particularly where the employee's annual income would normally attract a Personal Allowance. 0T typically applies in specific situations (redundancy, director cases, temporary fixes during coding review); checking the PTA promptly to correct it avoids excess deductions.