Tax code calculators

Emergency tax code: how much comes back

Independent site, not HMRC. Only HMRC can change your code: use your HMRC online account or app.

Your payslip shows W1, M1, X or NONCUM: the tax taken so far, the tax that was due, and the pay where the difference returns.

Usually 1257L if this is your only job.

1 = April, 6 = September, 12 = March.

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Should come back to you

£620.40

In your November pay (month 8), if the new code reaches payroll by then.

Tax on 1257L M1£620.40
Tax with 1257L over the same pays£0.00
Tax line on that payslip−£620.40
Check your code with HMRCHow this is worked out

Assumes no other pay earlier in the tax year. With a P45 from an earlier job, the refund depends on the tax already paid there.

An emergency tax code is your normal code run on a week 1 or month 1 basis: for 2026 to 2027 HMRC's P9X notice sets it at 1257L W1 or 1257L M1, shown as X when pay dates vary or as NONCUM by some payroll software. Each pay gets only one week's or one month's allowance, £1,048.26 a month, as if it were the first pay of the year. Someone who starts a job in September after months without work loses the allowance of April to August while the emergency code runs. With £2,600 a month and two months on 1257L M1, £620.40 is taken where the cumulative 1257L would have taken £0.00, so £620.40 should come back in one go on the first payslip that uses the proper code. HMRC usually sends that code once it has your details, which can take up to 35 days after you start.

Month 1 basis against cumulative

First pay, 1257L M1

£310.20

First pay, 1257L cumulative£0.00
Difference on that pay£310.20
Free pay used by cumulative£6,289.56

Cumulative counts the allowance of the months before the job started.

Tax on any payslip →

Rules read on HMRC’s texts by Radif Partners · Editorial policy · Method

Why the emergency basis takes more

A normal code is cumulative: the payroll adds your pay since 6 April, takes off the free pay for every month of the year so far and charges tax on the rest. The emergency basis cuts that link. Each pay is treated in isolation, with the free pay of week 1 or month 1 only, and the tax already paid is never compared with the tax due for the year (PAYE specification, paragraph 8). For someone who earns the same amount from April, the two methods give almost the same tax. For someone who starts in the middle of the year, or whose pay goes up and down, the emergency basis takes more, because the unused allowance of earlier months is ignored.

The table shows the effect of two monthly pays of £2,200 on 1257L M1, depending on the month the job started, compared with plain 1257L over the same two months, with no other income earlier in the year.

Two monthly pays of £2,200, 2026 to 2027, HMRC's payroll method.
First payOn 1257L M1Due with 1257LComes back
Month 1£460.40£460.60£-0.20
Month 4£460.40£0.00£460.40
Month 6£460.40£0.00£460.40
Month 9£460.40£0.00£460.40

When an employer uses an emergency code

A new employer needs your previous pay and tax to use the right code. If you hand over the P45 from your last job, parts 2 and 3 give them the code and the figures. Without it, you fill in the starter checklist: statement A, first job since 6 April with no Jobseeker’s Allowance, Employment and Support Allowance or Incapacity Benefit since then, leads to 1257L on a cumulative basis; statement B, this is now your only job but you had other pay this year, leads to 1257L on a week 1 or month 1 basis; statement C, another job or a State, workplace or private pension, leads to BR. GOV.UK also says you may be put on an emergency code when company benefits or the State Pension start, so that the tax for the year comes out right (emergency tax codes).

Starter checklist: which code?

Code the employer uses

1257L M1

Tax in the first month£310.20
Basismonth 1, until HMRC sends a code
Emergency tax calculator →

What to do while you are on it

Give the P45 to the new employer if you have it, or ask the previous employer for it. Check that your new job appears in your HMRC online account, and add the previous job's figures if they are missing. After 35 days, if the code still ends in W1, M1 or X and you think it is wrong, update your details there or contact HMRC (GOV.UK). Once HMRC issues the new code, it reaches you and your employer within 15 working days, and a monthly payroll should use it on the next or the following payslip; a weekly one on the third.

The refund appears as a negative tax figure, or a much lower one, on that payslip. If it does not, put the old and new payslips side by side and use the payslip calculator for the period number shown, to see what the cumulative code should give. A refund left at the end of the year comes through a P800 letter instead.

Common questions

How long does an emergency tax code last?

Usually until HMRC has the income details from your new and previous employers and sends a proper code, which can take up to 35 days from the start of the job. Where too little tax has been paid, GOV.UK says the emergency code may stay in place for the rest of the tax year, with a normal code from the new year.

Do I get emergency tax back automatically?

Yes, in most cases. When the cumulative code reaches your payroll, the software compares the tax due to date with what you paid and gives the difference back on that payslip. If the year ends before that happens, HMRC works out the difference after 5 April and sends a tax calculation letter that explains how to get the refund.

Is BR an emergency tax code?

Not in the W1 or M1 sense. BR is what an employer uses when the starter checklist says you have another job or pension. It is cumulative but has no allowance at all, so if this is in fact your only job, BR takes 20% from the first pound and the overpayment comes back once HMRC corrects the code.

Why did my emergency code not give a refund when it changed?

Because the cumulative code only gives back what the year so far allows. If an earlier job already used your allowance, or you were paid in the same month by two employers, the tax due to date may be close to what you paid. In that case the new code mainly corrects future pay, and anything left is settled after the year ends.

Next steps

W1, M1, X

Codes ending in W1, M1, X or NONCUM: each pay taxed on its own, and why that can cost you until the code changes.

New job

P45 or starter checklist: the code your new employer uses on the first payslip and how long the switch takes.

No P45

Lost or never sent: the code a new employer uses without a P45, and how the extra tax comes back.

Refund after a wrong code

Overpaid on the wrong code: the refund in your pay, or the P800 route after April, with the time each one takes.

Tax per payslip

The tax on one payslip by HMRC’s cumulative method: free pay, taxable pay and tax to date.

Where these rules were read

Written by

Independent publisher of free PAYE tax code checkers for employees and pensioners in the United Kingdom: what each code means, tax per payslip and emergency codes

Rates and rules checked on · Editorial policy · Contact

Tax codes 2026, read on HMRC’s payroll specification, GOV.UK and the rates for employers, last checked on