When One Spouse Has Spare Personal Allowance: Marriage Allowance for 2026/27

Marriage Allowance is often described as a tax break for married couples, but that shorthand can mislead. It is not a universal payment or a blanket discount. It is a transfer of part of one person's Personal Allowance to their spouse or civil partner, and it produces a saving only when the couple's circumstances line up in a particular way. For 2026/27, the transferable amount is £1,260, and the maximum saving is £252.

What the allowance actually does

Every individual in the UK has a Personal Allowance: the amount of income they can receive before income tax starts. For 2026/27, the standard Personal Allowance is £12,570. Marriage Allowance lets the lower-earning partner transfer 10% of that allowance — £1,260 — to the higher-earning partner.

The mechanics are straightforward. The transferor's allowance falls to £11,310, while the recipient's rises to £13,830. The recipient then pays less income tax, typically through an adjusted tax code. At the basic rate of 20%, the £1,260 transfer is worth £252 in the year. HMRC describes £252 as a maximum because the exact benefit depends on the recipient's tax position.

This is a tax reducer, not a cash grant. You cannot claim it and receive £252 if you have no income tax liability to reduce. That point matters for couples where both partners have low incomes, or where the recipient's income is already below their Personal Allowance.

Who can claim in 2026/27

The eligibility rules are narrower than the headline suggests. Four conditions do most of the work.

First, both of you must be married or in a civil partnership. Living together does not count, however long-standing the relationship. There is no unmarried-partner equivalent to Marriage Allowance.

Second, the partner transferring the allowance must have income of £12,570 or less for 2026/27. In practice, they must have unused Personal Allowance. If their income is above that level, they are using their allowance themselves and there is nothing to transfer.

Third, the recipient must not be liable to higher or additional rate income tax. Broadly, they need to be a basic-rate taxpayer for the year. If their income takes them above the higher-rate threshold that applies to them, the claim is not available. The threshold is not the same across the UK, so check the position for the part of the UK where you pay tax.

Fourth, only one transfer is allowed per couple. You cannot transfer in both directions. If both partners have unused allowance, only one transfer can be made in a tax year.

There are also residence rules for couples living abroad. If that applies to you, check the position with HMRC rather than assuming the UK rules apply in the usual way.

How to claim through HMRC

The claim is normally started by the partner who is giving up the allowance. HMRC's online Marriage Allowance service is the standard route. You will need identifying information for both partners, including National Insurance numbers, and HMRC will check the claim against its records.

If you cannot use the online service, HMRC can deal with the claim by phone or post. The process is not automatic. Marriage is not the trigger; a claim is.

Once the claim is accepted, HMRC adjusts the recipient's tax code to reflect the extra allowance. The transferor's code is also adjusted. You may see tax code M on the recipient's side and tax code N on the transferor's side. These codes are a signal that the allowance has been moved, but they are not proof that the claim is correct for every year.

If either partner completes a Self Assessment return, the allowance may be reflected through the return rather than solely through a tax code. Check that the claim has actually been applied. Do not assume that because HMRC has processed a code change, the same treatment will flow automatically into a return without review.

Backdating a claim

Marriage Allowance can be backdated by up to four previous tax years. An application made during 2026/27 can potentially cover 2022/23, 2023/24, 2024/25 and 2025/26, as well as the current year. The four-year limit means that a claim for 2022/23 needs to be on HMRC's radar by 5 April 2027.

Backdating is not automatic. HMRC will check that you met the conditions in each year. Couples whose incomes have changed over time may find that they qualify in some years but not others. A backdated claim can produce a refund, but only for tax that was actually paid and only where the allowance was available.

This makes backdating worth checking carefully. A couple who have been married for several years and only recently realised that one partner had unused allowance may be able to recover more than the current year's £252. The paperwork is modest, but the claim needs to be accurate.

The pitfalls that catch couples out

One common mistake is assuming that cohabitation qualifies. It does not. Another is assuming that the claim continues safely forever. Once in payment, Marriage Allowance normally continues automatically, but it is not a set-and-forget arrangement. A pay rise for the transferor, a change in the recipient's tax rate, or a change in marital status can all affect entitlement.

If the transferor's income rises above £12,570, they no longer have unused Personal Allowance to transfer. If the recipient becomes liable to higher or additional rate tax, the claim is no longer available. In either case, HMRC should be told promptly. Leaving an invalid claim in place can lead to an underpayment of tax that has to be repaid later.

Changes in circumstances matter too. Divorce, dissolution of a civil partnership, separation and bereavement can all affect entitlement. A claim should not simply be left running without review. If you are unsure how a change affects the current year and earlier years, ask HMRC or a tax adviser.

There is also an overlap with Married Couple's Allowance. Married Couple's Allowance is a different relief, available in limited circumstances to couples where at least one partner was born before 6 April 1935. You cannot claim both Marriage Allowance and Married Couple's Allowance for the same couple. If you think either relief might apply, check before submitting a claim.

Finally, remember that a refund cannot exceed the tax actually paid. A backdated claim may look generous on paper, but if the recipient had little or no income tax liability in an earlier year, there may be nothing to refund for that year.

A practical check before you apply

Look at both partners' expected income for 2026/27. Confirm that one is at or below £12,570 and that the other is not liable to higher or additional rate tax. Check whether either partner already has a Marriage Allowance claim in place. If you are claiming for earlier years, have the relevant income figures to hand.

Marriage Allowance is a targeted relief. It rewards a specific combination of circumstances: marriage or civil partnership, one unused Personal Allowance, and a basic-rate taxpayer on the other side. Where those conditions are met, the claim is simple and the saving is real. Where they are not, the claim can create more admin than benefit. Checking the basics first is the practical approach for 2026/27.