Marriage Allowance is one of those tax breaks that's been around since 2015 and yet millions of eligible couples still haven't claimed it. The concept is simple: if one partner doesn't use their full personal allowance, they can transfer a slice of it to the other partner, saving the household up to £252 a year. And you can backdate it.
Who qualifies
You can claim Marriage Allowance if all of these apply:
- You're married or in a civil partnership
- One partner earns less than £12,570 (the personal allowance)
- The other partner is a basic rate taxpayer — earning between £12,571 and £50,270
The lower earner transfers £1,260 of their personal allowance to the higher earner. This reduces the higher earner's tax by 20% of £1,260, which comes to £252. It's not going to change your life, but over four years of backdating that's over £1,000 sitting there unclaimed.
You can't claim if the higher earner pays tax at the higher rate (40%) or additional rate (45%). The transfer only works at the basic rate.
How to apply
The lower-earning partner applies through GOV.UK. You'll need both partners' National Insurance numbers. The process takes about 10 minutes online. Once approved, the transfer continues automatically each year until you cancel it or your circumstances change.
HMRC adjusts the higher earner's tax code to reflect the extra allowance. You might notice your code change from 1257L to 1382L — the number goes up because your tax-free amount has increased.
Backdating your claim
You can backdate a Marriage Allowance claim by up to four tax years. So if you apply in 2025/26, you can claim for 2021/22, 2022/23, 2023/24, and 2024/25 as well. HMRC sends the backdated amount as a lump sum cheque or bank transfer to the lower earner, while the ongoing saving is applied through the higher earner's tax code.
The backdated payment can be over £1,000 for couples who've been eligible for the full four years. That's money you've already been entitled to — it just needs claiming.
Common scenarios
Marriage Allowance often applies when:
- One partner works part-time and earns below £12,570
- One partner is a stay-at-home parent with no taxable income
- One partner is retired with only State Pension below the personal allowance
- One partner is a student or between jobs
Interestingly, it also works if the lower earner has a small amount of savings interest that keeps them below the threshold. As long as their total taxable income is under £12,570, they qualify.
What happens if circumstances change
If the higher earner moves into the 40% tax bracket, you'll need to cancel the transfer — it only benefits basic rate taxpayers. If you divorce or dissolve your civil partnership, the transfer ends. And sadly, if one partner passes away, the surviving partner can still claim for the period the marriage was in effect, including backdating.
Cancelling is straightforward through GOV.UK. It takes effect from the start of the next tax year.
Watch out for scam refund companies
You don't need to pay anyone to claim Marriage Allowance. The GOV.UK application is free and takes minutes. Despite this, companies still advertise "tax refund" services that take a percentage of your claim. MoneySavingExpert regularly warns about these — do it yourself and keep the full amount.