While more than 2.1 million couples claim marriage allowance, HMRC estimates that up to 2.4m couples are missing out because they do not realise they may be eligible, particularly couples where one partner has retired, has given up work to take on caring responsibilities, or is unable to work due to a long-term health condition.

All claims should be made on HMRC and do not use a third party provider as they will take a large cut of the allowance through commission fees.