If one spouse earns under £12,570 and the other is a basic-rate taxpayer, transfer £1,260 of personal allowance and save up to £252 a year. Backdate up to four years.
The non-taxpayer side of the household - usually under the personal allowance.
Must be a basic-rate taxpayer for the transfer to save tax - higher-rate disqualifies.
HMRC will backdate up to four prior tax years on first application, paid as a lump sum.
This year plus the backdated lump sum
Annual saving: £252. Apply via HMRC online. Backdating gives a further £1,008 lump sum. Total this year: £1,260. Five minutes online; the application carries forward until you opt out.
Uses 2025/26 HMRC figures: Personal Allowance £12,570, basic-rate band top £50,270, transferable amount £1,260, basic rate 20%. Backdating up to four prior tax years is automatic on first application. Re-apply not needed each year, carries forward.
Worth runs the Marriage Allowance check (and dozens of other UK reliefs) against your real numbers every year. Join the waitlist.
Online via the HMRC Marriage Allowance service - takes about five minutes. Backdating up to four prior tax years is automatic if eligibility was met in those years. Total backdated payment can reach £1,260 paid as a cheque or transfer. The allowance carries forward without re-applying until circumstances change or you opt out.
If the lower earner uses some of their personal allowance, transferring £1,260 of it can push them into paying basic-rate tax on the slice they were using. The net household saving is £252 minus that extra tax. The calculator nets this off automatically - sometimes the answer goes to zero before the income threshold.
Because the transfer only saves tax at the basic rate. A higher-rate taxpayer pays 40% on the slice covered by the transferred allowance, but the transferred allowance only saves at 20% - so on net they would pay more. HMRC disqualifies higher-rate taxpayers from the allowance for this reason.