Marriage Allowance lets you transfer 10% of your Personal Allowance (£1,260 in 2025/26) to your spouse or civil partner. To qualify: you must be married or in a civil partnership, the lower earner must have income below the Personal Allowance (£12,570), and the higher earner must be a basic rate taxpayer (income below £50,270). The tax saving is £252 per year at the 20% basic rate.