What does the tax code
1131N mean?

1131N is the other half of a Marriage Allowance claim. Somebody in your household is on a code like 1383M and paying £252 a year less tax. You are the reason. You transferred £1,260 of your Personal Allowance to them, so your own tax-free pay for 2026/27 has fallen from £12,570 to £11,310.

Whether that was a good idea depends on one number: what you earn. For a lot of couples this transfer is worth the full £252. For a surprising number, it is worth precisely nothing.

The arithmetic

The scheme is designed on the assumption that you were not going to use that £1,260 anyway. HMRC's condition for the lower earner is that their income is "normally below your Personal Allowance", so in the intended case you give away allowance that would have gone to waste and your partner turns it into a £252 saving.

The design breaks down when the giver's income is higher than expected.

When 1131N is worth the full £252, and when it is worth nothing

Your allowance dropping by £1,260 only costs you money if you were actually going to use that £1,260. Below £11,310 you have allowance to spare and the transfer is free to you. Above £12,570 you were using every penny of the original allowance, so giving £1,260 away costs you exactly £252, cancelling out your partner's gain.

Read the bottom three rows carefully. Once your income passes £12,570, the household gains nothing at all from the transfer. You lose £252, your partner saves £252, and the only thing that has changed is which of you paid it. The claim is not harmful, but it is pointless paperwork, and a great many people carry it for years without realising it stopped working.

Worked example: 1131N on a £12,000 income

Someone working part time on £12,000 who transferred their allowance while they were earning less.

1. Gross pay: £12,000
2. Subtract the 1131N allowance: £12,000 minus £11,310 = £690 of taxable income
3. Taxed at 20%: £138 of income tax
4. On a standard 1257L code they would pay nothing at all, because £12,000 is below £12,570

So the transfer costs them £138 while saving their partner £252. The household is £114 better off, which is a real gain but only half of what the scheme is meant to deliver. Income tax only, National Insurance excluded, and an estimate to confirm with HMRC.

If the same person's hours increased and their pay reached £14,000, the position changes: they would pay £538 rather than £286, a cost of £252, and the household gain would fall to zero.

The National Insurance point people miss

Marriage Allowance affects income tax only. National Insurance has its own thresholds and is entirely unaffected by the transfer, so nothing on this page changes what you pay in NI.

This matters because it is easy to look at a payslip after a transfer, see deductions you did not expect, and blame the tax code. If your pay crossed an NI threshold in the same period, the two changes arrive together and get conflated. The tax code explains the income tax line and nothing else.

How the transfer shows up in your pay

The timing catches people out, because the first year of a claim behaves differently from every year after it.

If the claim starts in April, your code is 1131N from the first payslip of the tax year and the effect is spread evenly. On the £12,000 example above, that is about £11.50 a month rather than a single visible event.

If the claim starts mid-year, the new code is applied cumulatively. Your employer recalculates the year from 6 April using the lower allowance, discovers you have had too much tax-free pay so far, and collects the difference in one go. A claim landing in month 9 can therefore produce one noticeably smaller payslip followed by normal ones. Nothing has gone wrong; the year has simply been rebalanced in a single step.

If the claim is backdated to earlier years, those years are settled separately from your code, usually as a calculation and a payment rather than a payroll adjustment.

In later years, the code arrives already set to 1131N in April and stays there. This is the point at which most people stop thinking about it, which is exactly why claims outlive their usefulness.

Why the number might not be exactly 1131

1131N assumes the standard allowance and nothing else going on. The N suffix can sit on any number, because it only tells you a transfer is running.

A £300 flat rate expense alongside the transfer gives £11,610 and a code of 1161N. A £500 benefit in kind deduction gives £10,810 and 1081N. If your code ends in N but the number is not 1131, read the coding notice rather than assuming an error.

When to cancel

Your income has risen above your Personal Allowance. As the table shows, the household gain has gone. Cancelling puts your own allowance back and costs your partner the £252 they were saving, so it is net neutral, but it removes an arrangement that no longer does anything.

Your partner is no longer a basic rate taxpayer. If their income passed £50,270 they are not eligible to receive the transfer, and the relief they have been getting will be recovered from them. This is the version that actually costs money, and it is the reason to review the claim after any promotion.

The relationship has ended. Cancellation rules differ depending on whether you divorced, dissolved a civil partnership, or separated, and on who cancels. It is worth handling deliberately rather than assuming it lapses.

One of you was born before 6 April 1935. Married Couple's Allowance is generally the better relief for those couples, and you cannot have both.

Claims renew automatically each year until cancelled. HMRC does not reassess your income as it changes, so a claim made when you earned £8,000 keeps running when you earn £30,000.

How to check and change it

Sign in to your Personal Tax Account at gov.uk/personal-tax-account and open "Check your Income Tax". The breakdown behind your code shows the transferred allowance as a deduction of £1,260. Your partner's code should show the matching addition with an M suffix.

Marriage Allowance is cancelled through HMRC's Marriage Allowance service. As the person who made the transfer, you are normally the one who has to do it. Our N tax code page covers the suffix generally and the 1383M page covers the receiving side.

Before deciding, it is worth putting both of your incomes through our free tax code checker so you can see the household position rather than one code in isolation. It produces an estimate, not advice, and HMRC has the final say.

Related tax codes: 1383M tax code | N tax code | M tax code | 1257L tax code | How to check your tax code

HMRC: Marriage Allowance