ISA Deadline April 5, 2026: What You Need to Do Before It's Too Late

Every year on 5 April, the UK tax year ends — and with it, your ISA allowance for that year disappears forever. You can save up to £20,000 tax-free in ISAs each tax year, but if you don't use it by the deadline, you lose it. The 2025/26 deadline is 5 April 2026. That's weeks away, and if you haven't maxed your allowance yet, now is the time to act.

Every UK adult gets a £20,000 ISA allowance each tax year. You can split this across different ISA types: Cash ISA, Stocks and Shares ISA, Innovative Finance ISA, and Lifetime ISA. Any interest, dividends, or gains you earn inside an ISA are completely free from tax — no income tax, no capital gains tax. Once the tax year ends, that year's allowance is gone and a fresh £20,000 starts on 6 April.

Log into your ISA provider and check your current year contributions. If you've paid in £8,000 since last April, you have £12,000 of allowance remaining. Even if you can only add a small amount before the deadline, it's worth doing — every pound inside an ISA grows tax-free, while every pound outside it doesn't.

As of March 2026, the best easy-access Cash ISA rates are sitting around 4.5–5% AER. Fixed-rate Cash ISAs for one or two years are slightly higher. Compare rates on MoneySavingExpert or MoneySuperMarket before depositing — switching to a better rate before 5 April can mean significantly more interest over the year. Many providers let you open and fund an ISA on the same day online.

If you're under 40 and saving for your first home or retirement, the Lifetime ISA is one of the best deals in personal finance. You can pay in up to £4,000 per year and the government adds a 25% bonus — up to £1,000 free money annually. The 5 April deadline applies here too. A £4,000 contribution before the deadline means £5,000 in your LISA instantly. You must be between 18 and 39 to open one, but once open you can contribute until 50.

You don't need to max your allowance to benefit. Any amount you put into an ISA before 5 April is shielded from tax for life. Even £500 or £1,000 saved tax-free compounds significantly over decades. The key is not letting the deadline pass with unused allowance that you could have used. Think about what's sitting in low-interest current accounts or premium bonds that could do better inside a Cash ISA.

If you're investing for five years or more, a Stocks and Shares ISA lets your investments grow without capital gains tax. Platforms like Vanguard, Freetrade, and Trading 212 let you open and fund one in minutes. With the deadline weeks away, even a lump sum invested now gets the clock ticking on tax-free growth. Don't let the fear of market timing stop you — time in the market beats timing the market.

Here's what to do right now: 1) Check how much ISA allowance you've used this year. 2) Decide which ISA type suits your goals (Cash for short-term, S&S for long-term, LISA for home/retirement). 3) Compare rates or platforms. 4) Transfer money in before midnight on 5 April. 5) On 6 April, your fresh £20,000 2026/27 allowance starts — plan how you'll use that too.