Marriage allowance can you cash in? 3rd April 2020 The marriage allowance allows you to transfer £1,250 of your unused personal allowance to your husband, wife or civil partner in a given tax year. In order to qualify the one receiving the transfer must not be a higher rate tax payer and the lower earner must have income below their personal tax free allowance of £12,500. This transfer can reduce your tax bill by up to £250 in a tax year. You can backdate your claim 4 years therefore if you have not claimed then 5 April 2020 is the deadline for going back. You can apply online at https://www.gov.uk/apply-marriage-allowance.