Millions risk missing this HMRC tax deadline for April 2026

Financial experts say this is one of the most important moments in the money calendar, as key tax-free limits are wiped clean and start again – and anything unused is gone for good.

Brian Byrnes, Director of Personal Finance at Moneybox, said: “The tax clock has reset, and now is the time to take action. All tax allowances are being refreshed, so it’s a key moment to think about how best to use them to achieve your goals.”

1. Use your £20,000 ISA allowance before it disappears

The annual ISA allowance stands at £20,000, but it operates on a strict use-it-or-lose-it basis.

Byrnes warned: “Any portion you don’t use in the next 12 months is gone for good, so it’s important to make the most of it where you can.”

Cash ISAs can be useful for short-term savings goals, while Stocks & Shares ISAs are typically better suited to longer-term investing. Lifetime ISAs can also help first-time buyers or retirement savers thanks to a government bonus.

2. Don’t miss out on pension tax relief

Pensions remain one of the most tax-efficient ways to save.

You can contribute up to £60,000 per year (or 100% of your salary, whichever is lower), and benefit from government tax relief.

Byrnes explained: “A pension comes with the benefit of free money. For a basic rate taxpayer, every £80 you contribute becomes £100 thanks to tax relief.”

He added that higher earners can benefit even more, with relief of up to 40% or 45%, depending on their tax band.

3. Mix savings and investing for better returns

Experts say you don’t have to choose between saving and investing.

Splitting your ISA allowance between cash and investments can offer both stability and growth potential.

Byrnes said: “You can split your contributions between cash for security and stocks and shares for growth, getting the best of both worlds.”

While cash savings are lower risk, they may struggle to keep up with inflation. Investing, on the other hand, has historically delivered stronger returns over the long term.

4. Take advantage of the Lifetime ISA bonus

A Lifetime ISA offers a 25% government bonus on contributions.

That means saving £4,000 per year could earn you an extra £1,000 annually.

Byrnes said: “If you’re planning to buy your first home or boost your retirement savings, a Lifetime ISA can be a powerful way to grow your money.”

5. Use allowances for your children too

It’s not just your own tax-free limits that reset.

Junior ISAs allow parents to save up to £9,000 per year per child, completely separate from the adult ISA allowance.

Byrnes noted: “With regular contributions, this can build into a meaningful financial boost for your children’s future.”

6. Watch out for common tax mistakes

Experts also warn many investors are caught out by avoidable errors, especially around capital gains tax.

Michele Tieghi, founder of PsyFi Money, said: “One of the biggest misconceptions is that tax only applies when money hits your bank account.

“In reality, selling investments can create a tax bill even if you reinvest straight away.”

He added: “Missed reporting, poor record keeping or simple errors can quickly lead to penalties, interest and unexpectedly large tax bills.”

Tieghi also stressed the importance of using allowances before they reset: “Once the tax year ends, those allowances are gone for good – and that can mean paying tax unnecessarily.”