Marriage Allowance is one of the most under-claimed tax reliefs in the UK — worth roughly £252 a year, and available to more couples than actually use it.
Who qualifies
You need to be married or in a civil partnership, with one partner earning below the £12,570 Personal Allowance and the other a basic-rate taxpayer. The lower earner transfers 10% of their unused allowance — £1,260 in 2026/27 — to their partner.
What it’s actually worth
That £1,260 of extra tax-free allowance saves the receiving partner 20% of it — £252 a year — for as long as the couple remains eligible.
Easy to miss
Because it requires an active application through HMRC rather than being applied automatically, a genuinely large number of eligible couples simply never claim it. You can also backdate a claim up to four tax years if you were eligible but never applied.
See exactly how it changes your take-home with the Payslp salary calculator.
How to actually claim it
Apply directly through gov.uk — it takes a few minutes online, and once approved, it typically stays in place automatically for future tax years until you cancel it or your circumstances change.
Frequently asked questions
Can I backdate a claim?
Yes, up to four tax years, if you were eligible throughout but never applied.
What if we divorce or separate?
You need to cancel the transfer — it doesn’t end automatically, and continuing to claim after you’re no longer eligible can result in having to repay it.