The Marriage Allowance applies to married couples and civil partners where one partner does not pay Income Tax, usually because their income is below the personal allowance. For the 2025–26 tax year, this means the lower-earning partner must earn less than £12,570. The figures remain the same for the upcoming 2026-27 tax year.

The allowance allows the lower-earning partner to transfer up to £1,260 of their unused personal allowance to their spouse or civil partner. This transfer is only permitted if the recipient is taxed at no more than the basic rate of Income Tax. This means the higher-earning partner must usually have an income between £12,571 and £50,270. For those living in Scotland, the figures are somewhat different. 

By using the allowance, up to £1,260 of unused personal allowance can be transferred, resulting in a tax saving of up to £252 per year for the higher-earning partner, calculated at 20% of the amount transferred.

If you meet the eligibility criteria and have not yet claimed the Marriage Allowance, you can backdate your claim for up to four previous tax years as well as the current tax year. This could result in a total tax saving of up to £1,260 across all eligible years. Claims, including backdated ones and those for the current year, can be submitted online via GOV.UK.

At present, claims can be backdated to the 2021–22 tax year, meaning you may be able to claim for 2021–22, 2022–23, 2023–24, 2024–25 and the current 2025–26 tax year. This could result in a tax saving of up to £252 a year for up to five years. Claims, including backdated claims and applications for the current year, can be made online via GOV.UK.