UK tax deadline: how to make use of all your tax allowances

The tax year runs from 6 April to 5 April the next year. This means that the most crucial UK tax deadline occurs every April. That’s because there exist various annual allowances and tax reliefs that you need to make use of to legally mitigate your income tax bill and stop taxes devouring your investment returns. Most of these are ‘use it or lose it’ allowances with a 5 April deadline. It’s no good bemoaning in June that you should have filled your ISA allocation by 5 April, but you were too preoccupied by the Donald Trump Show or the Six Nations rugby! No point cursing if you create a £500 capital gains tax liability in July that you might have defused in March! Ch-ch-changes Of course you read Monevator. You know this kind of stuff. But it’s still all too easy to overlook something. Especially when the tax rules keep changing! (For example, the basic and higher rates of dividend tax were increased in April 2026. Remember?) Let’s run through a checklist of what to think about as the…