Marriage Allowance Calculator
Check if you're eligible for Marriage Allowance in 2025/26, calculate your £252/year tax saving, and see how much you can claim by backdating up to 4 previous years.
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How to Use This Calculator
Am I Eligible? tab
Enter each partner's annual income and confirm you are married or in a civil partnership. The calculator checks whether one partner earns below the Personal Allowance (£12,570) and the other is a basic rate taxpayer (£12,571–£50,270). If eligible, you'll see the annual tax saving and how your tax codes change.
Backdate Claim tab
If you haven't claimed Marriage Allowance before, you can backdate up to 4 previous tax years plus the current year. Enter both incomes and the number of years to claim. The calculator shows a per-year breakdown and your total refund — up to £1,260 over 5 years.
Couple Tax Comparison tab
See your total tax as a couple with and without Marriage Allowance. The calculator compares both scenarios, shows your annual saving, and projects the long-term cumulative benefit over your chosen time horizon — including what the saving could grow to if invested.
Share your result
Every input is encoded in the URL. Click Share to send your exact scenario to your partner or save it for later.
The Formula
Marriage Allowance is a straightforward transfer of 10% of the Personal Allowance:
= £12,570 × 10% = £1,260
Tax Saving = Transfer Amount × Basic Rate
= £1,260 × 20% = £252 per year
Backdated Refund = £252 × Number of Years Claimed
Maximum = £252 × 5 = £1,260 (if eligible for all 5 years)
Lower earner's new PA = £12,570 − £1,260 = £11,310
Higher earner's new PA = £12,570 + £1,260 = £13,830
The lower earner gives up £1,260 of their Personal Allowance (which they weren't using anyway, since they earn below £12,570). The higher earner receives this £1,260 addition to their Personal Allowance, saving 20% tax on that amount — exactly £252 per year.
Because the lower earner's income is below the Personal Allowance, reducing their PA to £11,310 has no effect on their tax — they still pay £0. The saving is entirely one-sided and always benefits the couple.
Example
James & Emma — Married couple, Bristol
James earns £10,000/year working part-time (below the Personal Allowance). Emma earns £35,000/year as a project manager (basic rate taxpayer). They are married and haven't yet claimed Marriage Allowance.
How the transfer works
Backdating the claim
James and Emma have been married since 2020 and never claimed. They can backdate for 4 previous tax years plus the current year:
HMRC will send James and Emma a cheque for the backdated years and adjust Emma's tax code for the current year going forward.