Marriage Allowance Calculator

Marriage Allowance lets a non-taxpaying spouse or civil partner transfer £1,260 of their unused personal allowance to a basic-rate-taxpaying partner. That reduces the higher earner's tax by 20% of £1,260, up to £252 a year. It's designed for couples where one earns below the £12,570 personal allowance (so isn't using all of it) and the other earns between £12,571 and £50,270.

You must be married or in a civil partnership (living together unmarried doesn't count). One of you must be a non-taxpayer (income under £12,570), and the other a basic-rate taxpayer. It doesn't work if the higher earner pays higher-rate (40%) tax. The lower-earning partner makes the application, as they're the one giving up part of their allowance.

If you were eligible in previous years but never claimed, you can backdate up to four tax years. Combined with the current year, a first claim can be worth over £1,250 as a lump sum. Once set up, the allowance transfers automatically each year until you cancel it or your circumstances change, so you only apply once.

Transferring allowance can slightly increase the lower earner's own tax if their income is just under £12,570 (because they give up £1,260 of allowance). In most cases the couple is still better off overall, but if both incomes are close to the allowance it's worth checking. Tell HMRC if your income or relationship changes, as you may need to cancel.

• Not claiming at all. Millions of eligible couples miss out on up to £252 a year plus backdating.
• Using a paid claims company. They charge a fee for a free, few-minute HMRC application.
• Claiming when the higher earner is higher-rate. It only works if the higher earner is a basic-rate taxpayer.
• Forgetting to backdate. A first claim can include up to four previous years, don't leave that money behind.