The 2026/27 ISA deadline is 5 April 2027. Miss it and you lose that year's £20,000 tax-free allowance forever. Here's exactly what happens and what to do.
Overview
Every tax year, UK savers and investors get a £20,000 ISA allowance — money they can put into tax-free accounts where interest, dividends, and capital gains are completely invisible to HMRC. The 2026/27 tax year ends at midnight on 5 April 2027. After that, any unused allowance from this year vanishes. It doesn't roll over. It doesn't carry forward. It's gone. And yet, plenty of people miss the deadline every year. Some don't realise it exists. Some intend to act but leave it too late. Some think it doesn't matter because they don't have £20,000 to save. But the ISA allowance isn't all-or-nothing — even putting in £500 before the deadline is £500 earning tax-free interest that you'd otherwise pay tax on. Here's what actually happens when you miss it, why it matters more than you think, and what you can still do in the final weeks.
What exactly do you lose?
When the clock hits midnight on 5 April 2027, your 2026/27 ISA allowance expires. If you used £5,000 of your £20,000 allowance, the remaining £15,000 is gone — not deferred, not saved for later, just lost. On 6 April 2027, a fresh £20,000 allowance opens for the 2027/28 tax year, but that's a separate allocation entirely, and if you're under 65 only £12,000 of it can go into Cash ISAs. You cannot use it to 'catch up' on previous years. The financial impact depends on your tax situation. If you're a basic-rate taxpayer with modest savings, the Personal Savings Allowance (PSA) of £1,000 might cover your interest anyway. But if you're a higher-rate taxpayer (PSA of just £500), or your interest grows beyond your PSA, missing the ISA deadline means paying 20% or 40% tax on interest you could have earned tax-free (rising to 22% and 42% on savings income from April 2027). Over five or ten years, those missed allowances compound into thousands of pounds in unnecessary tax.
The real cost: a worked example
Let's say you have £10,000 in a standard savings account earning an illustrative 4% AER. That generates £400 in interest per year. As a basic-rate taxpayer, you'd pay no tax on this (it's within your £1,000 PSA). But keep saving and your pot grows. At £30,000, you're earning £1,200 in interest — £200 over your PSA. You'd owe £40 in tax on that excess. As a higher-rate taxpayer with a £500 PSA, the tax bill on £1,200 interest would be £280. Now imagine those same pots were in a Cash ISA. Tax owed: £0. Every year, forever. The ISA wrapper protects not just this year's interest, but every future year's interest on that money. The earlier you get money into an ISA, the more years of compound, tax-free growth you benefit from. Missing a single year's deadline might only cost you £40 in the short term, but over a decade of compounding, that missed opportunity grows significantly.
Can you still open an ISA before 5 April?
Yes — and it's easier than most people think. Most Cash ISAs can be opened online in under 10 minutes. App-based providers like Chip, Trading 212, and Moneybox let you open and fund an ISA entirely from your phone. You don't need to visit a branch. You don't need to post any forms. You need your National Insurance number, proof of UK residency, and a debit card. The important thing is that the money must be deposited, not just the application submitted, by 5 April. Some providers process deposits instantly (especially fintech apps). Traditional banks and building societies may take 1–3 working days. To be safe, aim to have everything completed a few working days before 5 April. Don't leave it to the wire.
I don't have £20,000. is it still worth it?
Absolutely. The £20,000 figure is a ceiling, not a target. Putting £100, £500, or £1,000 into an ISA is still worthwhile. That money will earn tax-free interest from the moment it's deposited, and it remains sheltered in future years as your savings grow. There's no minimum contribution where ISAs suddenly 'become worth it'. Every pound counts. Think of it this way: if you can save even £50 a month, that's £600 a year into an ISA. In five years, you'd have over £3,000 in tax-free savings (plus interest). In ten years, over £6,000. Start small, contribute regularly, and let compounding do the heavy lifting. The worst thing you can do is nothing because you think you don't have 'enough'.
What if you already have an ISA from a previous year?
ISAs from previous tax years keep their tax-free status indefinitely — they don't expire. Whether you can add new money to an older ISA depends on the account: many let you keep paying in each year, but some fixed-rate ISAs don't accept further deposits, in which case you'd open a new ISA for this year's allowance. You can also transfer previous years' ISAs to a new provider without affecting your current year's allowance. If your old ISA is earning a poor rate, now is a good time to transfer it to a better-paying account. Just use the official ISA transfer process — never withdraw and redeposit, as that would permanently lose the tax-free status on the transferred amount.
Types of ISA you can use before the deadline
Your £20,000 allowance can be split across different ISA types within the same tax year. Cash ISA: safest option, guaranteed returns, FSCS protected. Best for short-term savings and emergency funds. Stocks and Shares ISA: invest in funds, shares, and bonds. Better for long-term savings (5+ years) where you can ride out market fluctuations. Lifetime ISA: for first-time house buyers (under 40) or retirement savings. Contribute up to £4,000 per year and get a 25% government bonus (£1,000 free). Innovative Finance ISA: peer-to-peer lending. Higher potential returns but higher risk. Less common. If you're unsure, a Cash ISA is the simplest and safest choice. You can always transfer to a Stocks and Shares ISA later if your goals change. The critical thing right now is getting money inside the ISA wrapper before 5 April.
Common mistakes to avoid
Don't lose track of contributions across several accounts. Since April 2024 you can pay into more than one Cash ISA (or Stocks and Shares ISA) in the same tax year, but only one Lifetime ISA, and the £20,000 total covers everything. Going over could mean HMRC removing the excess from the ISA wrapper and taxing any interest on it. Don't withdraw from a flexible ISA after 5 April expecting to replace the money under this year's allowance. Flexible ISAs only allow withdraw-and-replace within the same tax year. Once the year ends, any withdrawn amount cannot be re-contributed without using next year's allowance. Don't confuse the ISA deadline with the self-assessment tax deadline (31 January). They're completely different dates for completely different purposes. The ISA deadline is about contributing to tax-free savings accounts, not about filing your tax return.
Five things to check on your ISAs now
- How much you have paid in since 6 April 2026. Add up payments across every ISA. You can pay into several ISAs of the same type in one tax year, but the combined total cannot exceed £20,000. The ISA allowance tracker keeps a running total.
- Your rate on easy-access Cash ISAs. Rates move with Bank Rate (3.75% at the time of writing, next decision on 5 November 2026). Many older ISAs pay far less than the best deals. Compare using our savings and Cash ISA hub.
- Fixed-rate ISAs maturing soon. Note the maturity date. If you do nothing, many providers move the money into a low-rate account.
- Old ISAs you could transfer. Transfers do not use any of this year's allowance as long as you use the provider's transfer process. Never withdraw and repay yourself, or the money loses its ISA status. See our ISA transfer guide.
- Whether your ISA is flexible. With a flexible ISA you can withdraw and replace money in the same tax year without it counting again. Not all providers offer this, so check before you take money out.
A month-by-month plan to 5 April 2027
Spreading payments avoids the March scramble and gets your money earning tax-free interest sooner. Work out how much of your £20,000 you have left, then divide by the payments remaining. Starting in November 2026 gives you five monthly payments before the March cut-off (aim to finish by mid-March, since some providers set earlier deadlines for transfers and debit card payments).
| Allowance left to use | 5 monthly payments (Nov to Mar) | Weekly equivalent |
|---|---|---|
| £2,000 | £400 | About £92 |
| £5,000 | £1,000 | About £231 |
| £10,000 | £2,000 | About £462 |
| £20,000 | £4,000 | About £923 |
Most people will not fill their allowance, and that is fine. The goal is to shelter what you can, not to hit £20,000. If you have savings sitting in a taxable account, moving them into a Cash ISA before 5 April 2027 is the simplest way to use the allowance. If you are saving from income, set a standing order for the day after payday and let the savings goal calculator tell you if you are on track.
Frequently asked questions
What people ask after the deadline has passed.
Can I carry over my unused ISA allowance to the next year?
No. The ISA allowance is use-it-or-lose-it. Any unused portion of your £20,000 allowance for 2026/27 expires on 5 April 2027 and cannot be carried forward or combined with the following year's allowance.
What is the next ISA deadline?
The deadline for using your 2026/27 ISA allowance is midnight on 5 April 2027. Your money must be deposited — not just applied for — by this date. It's sensible to complete deposits a few working days earlier to allow for processing times.
Can I open an ISA with just £50?
Yes. There is no minimum contribution where ISAs become 'worth it'. Many providers accept deposits as low as £1. Even small contributions earn tax-free interest and remain sheltered in future years as your balance grows.
Can I still use my 2025/26 ISA allowance?
No. The 2025/26 allowance ended on 5 April 2026 and unused allowance cannot be carried forward. You can now use your 2026/27 allowance of £20,000 until 5 April 2027.
When is the next ISA deadline?
5 April 2027, the last day of the 2026/27 tax year. Many providers set earlier cut-offs for transfers or card payments, so aim to pay in by mid-March.
Will the Cash ISA limit change in April 2027?
Yes. From 6 April 2027 under-65s can put up to £12,000 a year into Cash ISAs, within the unchanged £20,000 overall allowance. People aged 65 and over keep a £20,000 cash limit.
Will my existing Cash ISA savings be affected by the £12,000 limit?
No. The limit applies to new money paid in each tax year. Money already held in Cash ISAs keeps its tax-free status.
Does transferring an old ISA use up my allowance?
No. Transferring previous years' ISA money through your provider's transfer process does not count towards this year's £20,000. Withdrawing the money and paying it in yourself does count, and loses the tax-free wrapper on anything above your allowance.
- ISA deadline
- tax-free savings
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- UK finance
- April 2026