This tool is for illustration only. Tax rules are complex and your personal circumstances may differ. Always confirm figures with HMRC or a qualified tax adviser before acting.
Marriage allowance lets the lower-earning partner in a marriage or civil partnership transfer £1,260 of their unused personal allowance to their spouse. Because the higher earner gets tax relief at 20% on that £1,260, it saves £252 a year in income tax. Around 2.4 million eligible couples haven't claimed it.
The lower earner must have income at or below the personal allowance (£12,570 for 2026/27). The higher earner must be a basic rate taxpayer — income above the personal allowance but at or below the basic rate threshold (£50,270 in England, Wales and Northern Ireland; £43,663 in Scotland, which has its own income tax bands). Both partners must be married or in a civil partnership — cohabiting couples don't qualify, regardless of how long they've lived together.
The saving is fixed at £252 a year for as long as you remain eligible — it doesn't scale with income once you qualify. If you were eligible in previous tax years and never claimed, HMRC lets you backdate the claim up to four previous tax years, on top of the current year, so a first-time claim covering the maximum backdating window can be worth over £1,000 in one go.
It costs nothing and takes about ten minutes to apply online through HMRC. The lower earner must make the application — not the higher earner. Once set up, the allowance transfers automatically each year until you cancel it or your circumstances change. Check with HMRC or a tax adviser if your circumstances are unusual — this tool covers the standard case only.
Thresholds, the transferable amount, and eligibility rules are set by HMRC — see gov.uk/marriage-allowance for the current tax year's official figures.