Married couples or those in a civil partnership could save up to £252 a year by claiming marriage allowance.
Marriage Allowance is a benefit that some married couples are entitled to that can help them pay less tax. They could save up to £252 a year.
The benefit allows employees to transfer £1,260 of their personal allowance to their husband, wife or civil partner.
HMRC says that 2.1 million people across the UK currently benefit, but they estimate that thousands more could be eligible, but don’t realise.
Those who may not realise they may be eligible include couples where one partner has retired, has given up work to taken on caring responsibilities, or is unable to work due to a long-term health condition.
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Angela MacDonald, HMRC’s deputy chief executive and second permanent secretary, said: "We want every eligible couple to benefit from marriage allowance tax relief. Couples whose circumstances have changed – perhaps one of them has stopped working or taken a lower paid job – may not realise they are entitled to claim.
"It’s easy to find out what you may be due - search ‘marriage allowance calculator’ on GOV.UK to get started. By applying on GOV.UK, rather than through a third party, you get to keep 100% of the tax relief due."
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Upon successful application, HMRC will issue both individuals new tax codes to reflect the new allowances. The employee receiving the extra allowance will be issued with an ‘M’ tax code.
More information on marriage allowance can be found at GOV.UK.