Tax Code 1257L M1 Explained

What does 1257L M1 mean?

1257L is the default UK PAYE tax code for the 2026/27 tax year and is the code most employees in England, Wales and Northern Ireland will see on their payslip. The numeric portion 1257 is shorthand for your tax-free personal allowance: HMRC multiplies by ten to give £12,570 of income that is exempt from income tax across the year. Earnings above that threshold are taxed at the basic rate of 20% up to £50,270, the higher rate of 40% up to £125,140, and the additional rate of 45% above that. The trailing letter L tells your employer you are entitled to the full standard allowance with no adjustments for benefits, underpayments or reduced allowances. Because 1257L is a cumulative code, your employer recalculates the tax due on your year-to-date earnings every payday and smooths out any fluctuations from overtime, bonuses, sick pay or unpaid leave. That cumulative quality is what allows tax to balance out automatically — if your earnings dip in one month, you can recover overpaid tax in the next. If your code is anything other than 1257L it usually means HMRC is making an adjustment for benefits-in-kind, a previous underpayment, the Marriage Allowance, a second job, or because you live in Scotland or Wales. The M1 suffix changes how the code is applied. Instead of recalculating against year-to-date earnings every payday (the normal cumulative method), payroll treats each pay period as a fresh start. You receive 1/52nd (W1), 1/12th (M1) or one slice (X) of your tax-free allowance and basic-rate band each period, and any unused allowance from earlier in the year is ignored. That stops a refund being issued before HMRC has confirmed your figures, but it can leave you slightly overpaid until a cumulative code is reissued. M1 codes are almost always temporary holding codes that resolve within one or two pay cycles after your first FPS submission reaches HMRC.

Breakdown of the code

• 1257

  Number

  Multiply by 10 — £12,570 of tax-free personal allowance.

• L

  Letter

  Standard personal allowance with no special adjustment.

• M1

  M1

  Non-cumulative monthly basis. Each pay period is treated independently — no smoothing across the year.

Worked example

Operations analyst, single employment on £30,000 (paid monthly).

Roughly £290.50 income tax per month (~£3,486/year) before NI and pension.

Who should be on 1257L M1?

• New starters who could not provide a P45 and completed a starter checklist
• Employees whose previous employer reported their leaver pay late
• People returning to PAYE after self-employment or working overseas
• Cases where HMRC has paused a cumulative calculation pending a record review

Common problems

• Bonuses and one-off payments are taxed harder than under a cumulative code because unused allowance from earlier months is ignored.
• The code persists for three or more months — usually a sign HMRC has not received the FPS submission needed to reconcile your record.
• You have switched jobs and your former employer issued the P45 late, so the W1/M1/X code stays in place longer than it should.

What to do if 1257L M1 looks wrong

1. Provide your employer with a P45 from your previous job, or complete a starter checklist accurately (Statement A, B or C).
2. Wait one or two pay cycles — most emergency codes auto-correct as soon as HMRC receives the first FPS submission from your new employer.
3. If the code persists into a third payslip, sign in to your personal tax account and confirm both employments are listed correctly.
4. Phone HMRC on 0300 200 3300 quoting the date you started and the date your last job ended — they can issue a cumulative P9 the same day.
5. Once a cumulative code is reissued, any overpaid tax is refunded automatically through your next payslip.

If you should be on a different code…

Quick decision tree — when 1257L M1 is the wrong fit, here is the most likely correct code.

• If your previous employer has now filed your final FPS — you should be on 1257L.

  Standard personal allowance of £12,570 for England, Wales and NI.