Marriage allowance lets a person transfer part of their unused personal allowance to a spouse or civil partner. For 2026-27 up to 1,260 GBP (HMRC) can move across, provided the lower earner pays no tax and the higher earner is a basic-rate taxpayer.
In one line: Marriage allowance moves spare personal allowance from a non-taxpayer to a basic-rate partner to cut their tax.
How marriage allowance works
The transfer works when one partner earns below the personal allowance and the other is a basic-rate taxpayer. HMRC applies the transferred amount as a reduction to the recipient's tax bill rather than changing their income.
If one spouse earns 8,000 GBP, below the 12,570 GBP allowance, and the other earns 30,000 GBP, transferring 1,260 GBP (HMRC) for 2026-27 cuts the higher earner's tax by 20% of that figure, around 252 GBP for the year.
Claims can be backdated up to four tax years where the conditions were met. Once set up the transfer usually renews automatically until cancelled or until circumstances change.
Marriage allowance vs the personal allowance
The personal allowance belongs to each individual. Marriage allowance does not create extra allowance, it simply relocates a fixed slice of one partner's unused entitlement to the other.
It only helps when the lower earner cannot use their full allowance and the higher earner stays within the basic rate. If the higher earner pays tax above the basic rate, the couple is not eligible.
Primary source: GOV.UK: Marriage Allowance