A lot of couples in the UK aren’t getting the most from their Marriage Tax Allowance. Are you one of them? A wrinkle in the tax rules means that, if they’re eligible, married couples can save £252 in tax each year. If you missed the boat on this in previous years, you can even backdate your Marriage Allowance claim so you don't lose out! Right now, barely a quarter of eligible couples in the UK are taking advantage of their Marriage Allowance, and it's costing them real money. Let’s take a look at what the Marriage Allowance system’s all about.