How Marriage Allowance works
Marriage Allowance was introduced in 2015 to provide a modest tax break to couples where one partner does not use their full personal allowance. The logic is simple: if one person is not earning enough to use all of their £12,570 allowance, transferring part of it to their spouse lets the household pay less tax overall.
Who is eligible
To qualify, you must be married or in a civil partnership (cohabiting couples do not qualify). The lower earner must have income below the personal allowance of £12,570. The higher earner must be a basic rate taxpayer, their income must be between £12,571 and £50,270. Neither partner can be a higher or additional rate taxpayer.
What is transferred
The lower earner transfers exactly 10% of their personal allowance to their partner. For 2026/27 this is £1,257 (10% of £12,570). The lower earner's personal allowance reduces to £11,313 and the higher earner's increases to £13,827. The higher earner then pays 20% less tax on the additional £1,257 of income that is now covered by their increased allowance, saving £252.
How to apply
The lower earner makes the application through HMRC's online service at gov.uk/marriage-allowance. You need both partners' National Insurance numbers. Once approved, the higher earner's tax code is updated to reflect the additional allowance. The application can also include backdated claims for up to four previous tax years.
Backdated claims
If you were eligible in previous years but never claimed, you can backdate by up to four years. Claims covering 2022/23, 2023/24, 2024/25, and 2026/27 could total £1,008 paid as a lump sum. The lower earner still applies, and HMRC will adjust both partners' records accordingly.
Death of a spouse: Marriage Allowance can be backdated following the death of a spouse, even where the surviving partner is now a higher rate taxpayer. HMRC allows claims for years in which both conditions were met, regardless of later changes in circumstance.
Frequently asked questions
No. Marriage Allowance is only available to legally married couples and civil partners. Couples who live together but are not married or in a civil partnership are not eligible, regardless of how long they have been together or whether they share finances. This is one of the few remaining tax advantages that applies specifically to marriage and civil partnership in the UK tax system.
You must cancel the Marriage Allowance if the lower earner's income rises above £12,570. Because the lower earner now needs their full personal allowance, transferring part of it would result in them paying more tax than they save. HMRC will adjust both partners' tax codes once you cancel. You can do this through your Government Gateway account. If your income fluctuates around the threshold from year to year, you can reapply in years where you qualify and cancel in years where you do not.
Yes. It must be the lower earner who applies, because they are the one giving up part of their personal allowance. The higher earner cannot initiate the transfer, they are simply the recipient of the additional allowance. Both partners need their National Insurance numbers to hand when making the application. The saving then appears in the higher earner's tax code, reducing the amount of tax they pay on employment income through PAYE.
Yes, they are two completely different reliefs. Marriage Allowance (the transfer of 10% of the personal allowance) is available to all eligible married couples and civil partners regardless of age. Married Couple's Allowance is a separate, older relief available only where at least one partner was born before 6 April 1935, making it relevant only to older couples. Married Couple's Allowance is worth between £4,280 and £11,080 per year (2026/27) depending on income, and provides a tax reducer rather than an allowance transfer. You cannot claim both reliefs simultaneously.
Related calculators
Tax Toolkit UK provides free calculators for guidance purposes only. Results are estimates based on HMRC rates for the 2026/27 tax year. Individual circumstances vary. Always consult a qualified tax adviser before making financial decisions.