Marriage Allowance lets one spouse or civil partner who earns under the Personal Allowance transfer £1,260 of it to the other, cutting the higher earner's tax by up to £252 a year. The receiving partner must be a basic-rate taxpayer (income up to £50,270 outside Scotland).
Claims can be backdated up to four tax years, so a couple claiming for the first time can receive over £1,000. It is free to claim directly with HMRC and takes minutes; refund firms that offer to do it keep a large slice for no added value. The recipient's tax code gains an M suffix and the giver's an N.
One partner earns £9,000 from part-time work (below the Personal Allowance) and the other £32,000. Transferring £1,260 of allowance cuts the higher earner's tax by £252 this year, and backdating the claim four years brings the first payment to around £1,000. The claim takes about ten minutes on GOV.UK.
