When is the ISA deadline?

When exactly is the deadline?

The UK tax year runs from 6 April to 5 April. For the current tax year, that means your ISA allowance has to be used by midnight on 5 April 2027. After that moment, the 2026/27 allowance is closed, and a new one opens on 6 April 2027.

What does “use it or lose it” actually mean?

ISA allowance is not a balance you can save up. If you pay in £12,000 this tax year and nothing more, the remaining £8,000 of room does not add itself to next year’s allowance. You start 6 April 2027 with a fresh £20,000, regardless of how much of this year’s you used.

This is different from, say, unused pension annual allowance, which in some circumstances can be carried forward. ISAs do not work that way. There is no mechanism to reclaim a missed year.

Why the 2026/27 deadline is different from previous years

Every 5 April matters if you have not used your allowance, but this one carries extra weight. From 6 April 2027, the Cash ISA limit for savers who are 64 or under at the end of the tax year drops to £12,000, with the remaining £8,000 of the £20,000 total having to go into a Stocks and Shares ISA, an Innovative Finance ISA, or a Lifetime ISA instead.

Right up until 5 April 2027, none of that applies. The old rule still holds: you can put the full £20,000 into a Cash ISA if that is where you want your money, with no split required. If you are under 65 and cash is genuinely where you want this year’s savings, 2026/27 is the last tax year that choice is unrestricted.

If you are 65 or over at the end of the tax year in question, that is, your 65th birthday falls on or before 5 April of that year, this change does not apply to you. You keep the full £20,000 Cash ISA allowance for the whole year, backdated to 6 April, not just from your birthday onward.

Practical timing: your bank’s cut-off is not the government’s

The 5 April deadline is a legal one, but your provider’s own operational cut-off is usually earlier and is entirely down to them. Common reasons a payment can miss the deadline even if you started it on 5 April itself:

• Faster Payments and card payments can take a short time to clear and be accepted as a subscription, and providers may stop accepting new-money payments earlier in the day to protect their own processing.
• Cheques take several working days to clear, so a cheque posted on 3 or 4 April is unlikely to count for the year you intended.
• New account applications near the tax year end are often paused a few days early by providers dealing with a surge of last-minute savers.
• Standing orders and direct debits set up for a set date can fail or be delayed by weekends and bank processing schedules.

Weekends, bank holidays and this year specifically

In 2027, 5 April falls on a Monday and 6 April falls on a Tuesday, so there is no weekend or bank holiday sitting across the changeover this time. That removes one common source of last-minute problems, but it does not remove the provider cut-offs above. Do not assume “5 April is a normal working day” means “any payment on 5 April will definitely count.”

What to check before 5 April 2027

A few practical things are worth confirming well ahead of the deadline, not on the day itself:

• How much of your £20,000 you have used so far this year, across all your ISAs combined, not just the one you are looking at right now.
• Whether you are close to turning 65. If your 65th birthday falls on or before 5 April of the tax year in question, you get the full £20,000 Cash ISA allowance for that whole year once the £12,000 cap starts applying to under-65s, so the date you cross that threshold can change what makes sense for you.
• Whether a fixed-rate account you are considering accepts top-ups at all. Many fixed-rate Cash ISAs only take a single lump sum on opening, so if you plan to add money gradually in the run-up to the deadline, an easy access account may suit that period better, even if you move the balance into a fixed rate afterwards.
• Whether the Autumn Budget on 28 October 2026 changes anything. ISA rules have moved quickly before. Anything confirmed at that Budget for the 2026/27 or 2027/28 tax years would land after this page was last checked, so treat the detail here as current as of 29 September 2026, and confirm anything time-critical on gov.uk closer to April.

What if you miss it?

Nothing dramatic happens, but the allowance is simply lost. You cannot apply it retroactively, appeal for an extension, or make it up later in the new tax year on top of the new allowance. The only genuine safeguard is not to leave a large subscription until the final few days.