Written and reviewed by James Whitfield · Updated for 2026/27 · Editorial standards · Methodology
How the Marriage Allowance works, who qualifies, and how to claim a backdated refund.
Marriage Allowance lets one partner in a married couple or civil partnership transfer up to £1,260 of their personal allowance to the other. This only makes sense in one specific situation: when one partner earns below the personal allowance (£12,570 in 2026/27) and the other pays income tax at the basic rate (20%). The partner with the lower income transfers part of their unused allowance to the higher earner, who then receives a tax reduction of 20% of the transferred amount.
The maximum saving is 20% × £1,260 = £252 per year. That is £21 per month, modest, but real and recurring. You claim once and it stays in place year after year until your circumstances change, which makes the one-time admin effort clearly worthwhile if you qualify.
The transfer is one-directional: the lower earner applies to give up part of their allowance; the higher earner receives a revised tax code with a higher personal allowance. HMRC handles the adjustment through the PAYE system, so there is nothing to do annually after the initial claim.
You qualify if: you are married or in a civil partnership; one of you has income below the personal allowance of £12,570; and the receiving partner pays income tax at the basic rate (income between £12,571 and £50,270). Cohabiting couples who are not married or civilly partnered cannot use this allowance, that is a deliberate policy choice, not an oversight.
You do not qualify if the receiving partner is a higher-rate or additional-rate taxpayer. The idea is that the unused allowance would not go to waste at the basic rate if the recipient is already in a higher band. Somewhat counterintuitively, this means couples where one very high earner and one non-earner are living together are ineligible, while couples where one earns just over £12,570 and the other earns £30,000 do qualify.
Non-residents and situations where one partner has a different tax code for other reasons (for example, benefits in kind that reduce the allowance below £12,570) can complicate the calculation. If your tax code is already adjusted downward, you may be transferring an allowance you are not actually receiving in full.
The lower earner applies on the gov.uk website. You need both partners' National Insurance numbers and confirmation of the qualifying relationship. HMRC usually processes the claim within a few weeks and updates the receiving partner's tax code. On your payslip, the receiving partner's tax code will change from 1257L to 1383M, the M indicates the Marriage Allowance is included, and the effective personal allowance rises to £13,830.
You can backdate a claim for up to four years. For 2026/27, that means you can also claim for 2025/26, 2024/25, 2023/24, and 2022/23, collecting a lump sum for years you were already entitled but did not claim. At £252 per year, four years of backdating is worth just over £1,000, with the recent year often collected by adjusted tax code and earlier years paid as a direct refund to the lower earner.
The claim stays active until one of you cancels it, usually because circumstances change (the lower earner now earns above £12,570, or the higher earner moves into the higher rate band). HMRC will sometimes cancel automatically if your tax records change materially, but it is worth checking your tax code each April to confirm the allowance is still correctly applied.
Current tax-year thresholds used across this guide and calculator.
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