Nearly 1.8 million married couples and those in civil partnerships are using the Marriage Allowance to save up to £252 a year in income tax, according to HMRC.
Marriage Allowance allows married couples or those in civil partnerships to share their personal tax allowances if one partner earns an income under their Personal Allowance threshold of £12,570 and the other is a basic rate taxpayer.
They can transfer 10% of their tax-free allowance to their partner, which is £1,260 in the 2021 to 2022 tax year.
It means couples can reduce the tax they pay by up to £252 a year. Couples can backdate their claims for any of the four previous tax years, which could be worth up to a total of £1,220.
Angela MacDonald, HMRC's Deputy Chief Executive and Second Permanent Secretary, said: 'Marriage Allowance lets eligible couples share their Personal Allowances and reduce their tax by up to £252 a year. Nearly 1.8 million couples are already using the service – it is free, quick and easy to apply, just search 'marriage allowance' on GOV.UK.'