What the M and N letters mean
Marriage Allowance lets a lower earner transfer £1,260 of their Personal Allowance to their husband, wife or civil partner. HMRC marks both partners' tax codes so payroll knows a transfer is in place.
| Letter | Meaning | Who has it |
|---|---|---|
| M | You've received a transfer of 10% of your partner's Personal Allowance | The higher earner, who pays basic rate tax |
| N | You've transferred 10% of your Personal Allowance to your partner | The lower earner, whose income is below their Personal Allowance |
| L | The standard tax-free Personal Allowance, with no transfer | Most employees with one job |
HMRC's PAYE Manual uses the same rule when it sets codes: suffix M where someone has received 10% of their spouse's or civil partner's Personal Allowance through Marriage Allowance, suffix N where they have transferred it. A Scottish or Welsh taxpayer has an S or C in front, for example S1383M.
The numbers: 1383M and 1131N in 2026/27
The number in a tax code is the tax-free amount for the year with the last digit dropped: £12,570 becomes 1257. Marriage Allowance moves £1,260 from one partner to the other, so the numbers change as well as the letter.
| Person | Tax-free amount | Tax code |
|---|---|---|
| No Marriage Allowance | £12,570 | 1257L |
| Receiving Marriage Allowance | £12,570 + £1,260 = £13,830 | 1383M |
| Transferring Marriage Allowance | £12,570 − £1,260 = £11,310 | 1131N |
GOV.UK gives the £1,260 transfer and the giver's reduced allowance of £11,310; the code numbers above follow from HMRC's rule for turning an allowance into a code. Your own number can differ, because the code also carries any other adjustments: a company benefit, an unpaid tax bill or job expenses all move it. That is why some people see 1257M or 1257N. The letter tells you a transfer is in place; the number is your total tax-free amount after every adjustment, and the coding notice from HMRC lists each one.
What Marriage Allowance is worth on a payslip
Take an employee paid £2,500 a month in England, so £30,000 a year, all taxed at the 20% basic rate above the allowance.
| Tax code | Income Tax a month | Income Tax a year |
|---|---|---|
| 1257L | £290.20 | about £3,482 |
| 1383M | £269.20 | about £3,230 |
| Difference | £21.00 | £252 |
The extra £1,260 of allowance saves 20% of £1,260, which is £252 a year or £21 a month. National Insurance doesn't change: Marriage Allowance is an Income Tax relief only, so the NI line on the payslip stays the same.
The partner who gives the allowance usually loses nothing. If they earn £10,800 a year, both 1257L and 1131N leave them with no Income Tax to pay, so the couple is £252 a year better off. If they earn £12,000, the lower allowance of £11,310 means they pay 20% on £690, which is £138, and the couple gains £114 instead. Once the giver's income is above their Personal Allowance, usually £12,570, they can't claim.
When the code changes in the middle of the year
A new code can take up to two months to reach payroll after a claim. On a normal cumulative code, the first payslip under the new code gives back the allowance for the months already paid. In the example, if 1383M starts in month 7 (October), PAYE that month is £144.20 instead of £290.20: the £21 for October plus £126 for April to September, give or take a pound of rounding in HMRC's tables. From November the tax is £269.20 a month.
If the new code arrives with W1 or M1 after it (a non-cumulative code), there is no catch-up on the payslip, and any tax overpaid earlier in the year is put right after the tax year ends. Claims backdated to earlier years, which GOV.UK allows back to 6 April 2022, are refunded by HMRC directly, not through payroll.
Who can get Marriage Allowance
- You must be married or in a civil partnership. Living together isn't enough.
- The person giving the allowance must have income below their Personal Allowance, usually £12,570, or pay no Income Tax.
- The person receiving it must pay Income Tax at the basic rate, which usually means income from £12,571 to £50,270. In Scotland they must pay the starter, basic or intermediate rate.
The lower earner usually makes the claim online. You must cancel it if you divorce, end a civil partnership, legally separate, or stop being eligible; either partner can cancel when the relationship ends. If the receiving partner dies, their estate keeps the higher allowance for that year; if the giving partner dies, the survivor keeps it until 5 April and then returns to the normal allowance.
What employers should do with an M or N code
Use the code HMRC sends. An employer can't add or remove Marriage Allowance itself, and an employee asking for it should claim through GOV.UK. There is no separate Marriage Allowance line on a payslip: the only signs are the code and the lower Income Tax.
If an employee's code shows M but their tax hasn't fallen, check that payroll has applied the latest notice and whether other adjustments in the code have offset the transfer. If it still looks wrong, the employee should check their code in their HMRC online account or app, where each adjustment is listed.
Questions
What does M mean in a tax code?
M means you receive Marriage Allowance: your spouse or civil partner has transferred 10% of their Personal Allowance (£1,260) to you. In 2026/27 the code is usually 1383M.
What does N mean in a tax code?
N means you've transferred 10% of your Personal Allowance to your spouse or civil partner through Marriage Allowance. Your tax-free amount falls to £11,310, so the code is usually 1131N.
Is 1257M a correct tax code?
It can be. The M confirms you receive Marriage Allowance, and the number is your tax-free amount after all adjustments. If another adjustment, such as a taxable benefit, cancels out the £1,260, the code can read 1257M. Your HMRC coding notice shows the breakdown.
How much does Marriage Allowance save on a payslip?
Up to £252 a year in 2026/27, which is about £21 a month for someone paid monthly. It reduces Income Tax only, not National Insurance.
How long does it take for the tax code to change?
GOV.UK says the tax code change can take up to 2 months. On a cumulative code, the first payslip with the new code makes up for earlier months of the tax year.
Sources
- GOV.UK — Marriage Allowance
- GOV.UK — Marriage Allowance (eligibility, how it works, cancelling, if your partner dies)
- GOV.UK — Tax codes: what your tax code means
- HMRC PAYE Manual — PAYE11045: rules for deciding the code suffix
- HMRC PAYE Manual — PAYE11040: coding notice notes
- GOV.UK — Tax codes (updating your code, refunds through pay)
- HMRC — Rates and thresholds for employers 2026 to 2027
Official sources checked 29 October 2026. This guide explains how pay documents work; it is not tax or legal advice.
