Tax Code 1257M Explained

What does 1257M mean?

1257M is issued when your spouse or civil partner has transferred 10% of their personal allowance to you under the Marriage Allowance scheme. Your allowance becomes £12,570 + £1,260 = £13,830. To qualify, your partner must be a non-taxpayer (earnings below the personal allowance) and you must be a basic-rate taxpayer.

Breakdown of the code

• 1257

  Number

  Multiply by 10 - base allowance.

• M

  Letter

  Marriage Allowance recipient - allowance increased by £1,260.

Worked example

Basic-rate office worker with non-earning spouse on £30,000 (paid monthly).

£21 less tax per month than 1257L.

Who should be on 1257M?

• Basic-rate taxpayers whose non-earning spouse has applied to transfer 10% of their personal allowance

Common problems

• Your partner started earning above the personal allowance - Marriage Allowance is no longer beneficial.
• You moved into the higher-rate band - eligibility ends and HMRC will reissue a standard code.

What to do if 1257M looks wrong

1. Sign in to your HMRC personal tax account at gov.uk/personal-tax-account and open the latest P2 (Notice of Coding) - it itemises every adjustment.
2. Compare the code on your most recent payslip with the code HMRC has on file; employers occasionally apply an old code if a P9 was missed.
3. Confirm your employer received your P45, or that you completed a starter checklist if you joined mid-year.
4. Check whether benefits-in-kind such as a company car, fuel, or medical insurance have changed and ask payroll to file an updated P11D.
5. Call HMRC on 0300 200 3300 (Mon-Fri, 8am-6pm) with your National Insurance number if the online tools cannot resolve it.
6. If you have overpaid, HMRC normally refunds via your next payslip once the code is corrected. For closed years request a P800 review.

If you should be on a different code…

Quick decision tree - when 1257M is the wrong fit, here is the most likely correct code.

• If you have a single PAYE job and no benefits-in-kind - you should be on 1257L.

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