There is a quiet bit of the UK tax system that pays a married couple or civil partners up to £252 a year, asks for about ten minutes of admin once, and then keeps paying every year after that without another form. Most people who qualify for Marriage Allowance have simply never heard the phrase, or assumed it was one of those reliefs that vanished a few Budgets ago. It did not. It is still running in the 2026/27 tax year, the personal allowance it is built on is still frozen at £12,570, and HMRC will still let you reach back four tax years to claim what you missed.
The catch is that nobody writes to you about it. Your payroll software will not flag it, your bank will not mention it, and the eligibility test depends on two people's incomes rather than one — so it falls between the cracks of how tax is usually handled. If one partner stays at home with young children, works part-time, has retired early, or is on a modest pension, this is very often money sitting unclaimed.
What Marriage Allowance actually does
Every UK taxpayer gets a personal allowance — the slice of income taxed at 0%. For 2026/27 that figure is £12,570, the same frozen number it has been since April 2021. Marriage Allowance lets the lower-earning partner give away 10% of their personal allowance, which works out at £1,260, to the higher-earning partner. The receiving partner's allowance goes up by that £1,260, so £1,260 less of their income is taxed at 20%. Twenty per cent of £1,260 is £252, and that is the headline saving.
It is worth being precise about the direction of travel here, because the wording trips people up. The person who gives up part of their allowance has to be the lower earner — usually a non-taxpayer. The person who receives it has to be a basic-rate taxpayer. If you flip those roles, the maths does not work and HMRC will not accept the claim.
Do you actually qualify?
Three conditions have to hold at the same time. You must be married or in a civil partnership — simply living together does not count, however long you have been together. One partner must earn below the £12,570 personal allowance (or have income low enough that they pay no income tax). The other must be a basic-rate taxpayer, which in England, Wales and Northern Ireland means taxable income between £12,571 and £50,270.
Scotland is the exception that catches people out. Because Scotland sets its own income tax bands, the receiving partner qualifies if they are a starter, basic or intermediate-rate Scottish taxpayer — broadly income up to £43,662 for 2026/27. The principle is the same; the threshold is just lower. If the higher earner has tipped into higher-rate tax, you lose eligibility entirely, and there is no partial version.
A common real situation: one partner left work to look after a new baby and now has no taxable income, while the other earns £34,000 at a desk job. That couple qualifies cleanly, and the £252 is theirs for every full tax year the arrangement holds.
The backdating window people miss
This is the part worth setting a reminder for. You can backdate a Marriage Allowance claim by up to four tax years, provided you were eligible in each of those years. As things stand in 2026, that means claims reaching back to the 2022/23 tax year are still open. The annual saving has hovered around the £250 mark across those years because the personal allowance has been frozen the whole time, so a full backdated claim plus the current year can add up to something north of £1,200 paid as a lump sum.
HMRC pays backdated amounts either as a cheque, a bank transfer, or by adjusting the receiving partner's tax code so they pay less over the rest of the year. You do not choose a separate "backdate" button — you tick the earlier years when you apply, and the system works out what is owed.
How to claim without paying anyone
Apply directly through GOV.UK and it costs nothing. Search "Marriage Allowance" on gov.uk, and the lower-earning partner makes the application using their Government Gateway login, their National Insurance number, and a way to prove identity — usually a recent payslip, a P60, or passport details. The whole thing genuinely takes about ten minutes if your documents are to hand.
Avoid the cluster of websites and "tax rebate" firms that advertise to handle Marriage Allowance claims for you. They are not doing anything you cannot do yourself, and they typically skim a percentage — sometimes a large one — off the refund. Some operate on the edge of misleading, signing people up to broader deeds of assignment that hand them a cut of all future rebates, not just this one. There is no version of this where a third party is the better choice. Go to the source.
Once it is set up, leave it alone — mostly
One of the genuinely good things about Marriage Allowance is that it renews automatically. Set it up once and it carries forward year after year, so you are not re-applying every April. But automatic renewal is also where it can quietly go wrong, and this is the edge case worth knowing. If the lower earner's income rises above the personal allowance, or the higher earner gets a pay rise into higher-rate tax, the arrangement can start costing one of you money rather than saving it — and HMRC will not always catch the change in real time.
So treat a meaningful change in either income as the trigger to check. A promotion, a return to full-time work, a new pension drawdown — any of those can shift the maths. You can cancel or adjust the transfer through your Personal Tax Account, and if a partner dies, the surviving partner can still claim for the relevant years. Set the claim, pocket the backdated lump sum, and put one calendar note against the next time either of your salaries jumps.