The ISA deadline and the end of the tax year

The ISA deadline falls at midnight on 5 April each year. The tax year ends on 5 April and you must use all of your ISA allowance by that date or lose it¹. During the 2026-27 tax year, which runs from 6 April 2026 to 5 April 2027, you can place up to £20,000 into an ISA², and HMRC has confirmed the annual subscription limit will remain at £20,000 until April 2031³.

That £20,000 is a use-it-or-lose-it allowance. It does not roll over from one tax year to the next, and your allowance resets every 6 April⁴. Money you leave in an ordinary savings account, or sitting in a current account waiting for a better moment, cannot be given last year's allowance once the year has turned: from 6 April it counts against the new year's £20,000 instead.

The deadline matters most in the closing weeks of the tax year, when providers see a rush of deposits and transfers. Transfers between providers are supposed to be completed within 30 calendar days, so a transfer started in mid-March may not finish before the year end, and a payment made on 5 April itself needs to have reached the provider by the time the year closes. This page explains how the year end works, what counts towards the allowance, and what happens to anything left unused.

The ISA deadline: midnight on 5 April

The tax year ends on 5 April every year, and any ISA allowance not used by that date is lost¹. In practice the deadline is the moment the tax year closes: the last moment to subscribe against the 2026-27 allowance is midnight at the end of 5 April 2027, and the new allowance begins on 6 April².

What catches many people out is that "paying in before the deadline" means the money must count as subscribed in that tax year, not simply that you have started the process. A bank transfer sent late on 5 April may not clear until 6 April or later, and it is the provider's records of when the subscription was made that determine which tax year it falls into. Providers can also get busy in the final days, and some close their processing earlier on the last day than on an ordinary weekday. If a payment is time-critical, the safe approach is to make it days rather than hours before the deadline and to confirm with the provider that it has been received and counted.

The same pressure applies to transfers. A stocks and shares ISA transfer should be completed within 30 calendar days of instruction under HMRC guidelines⁶, and the regulations require a transfer or withdrawal of funds and investments to take place within 30 days of instruction unless an exception applies⁷. A transfer instructed in early March therefore has a reasonable chance of completing before 5 April; one instructed in the final week may not. Transfers that straddle the year end do not lose allowance, but they can leave money in limbo between providers for a period.

How the tax year works

The UK tax year is a legal construct with slightly odd dates, and it is those dates that create the ISA deadline. In legislation, a "tax year" means a period beginning with 6th April in one year and ending with 5th April in the next⁸. The 2026-27 tax year therefore runs from 6 April 2026 to 5 April 2027, and every ISA allowance, from the adult £20,000 to the Junior ISA limit, applies to that window rather than to a calendar year.

The reason the dates sit mid-week and mid-month goes back centuries, but the practical effect is simple: everything tax-related, from ISA allowances to pension input periods, runs on the same 6 April to 5 April cycle. Your ISA allowance is refreshed once a year, on 6 April, and everything you pay in between that date and the following 5 April counts against the same limit.

The closing months of the tax year have become known in the industry as "ISA season". The first ISA season runs from January to March as the end of the tax year approaches and people rush to use their allowance⁹. Providers respond with their most competitive rates and offers in this window, and promotional activity tends to peak in the final weeks. For a saver who has not yet used their allowance, this is both the busiest and often the most rewarding time to act, but it is also when providers are at their most stretched, which is another reason not to leave things to the last day.

The £20,000 ISA allowance and what counts towards it

The headline figure is £20,000 per tax year. During the 2026-27 tax year you can place up to £20,000 into an ISA², and HMRC has stated that the ISA annual subscription limit will remain at £20,000 until April 2031³. The Budget 2025 documents confirm the same picture: annual subscription limits will remain at £20,000 for ISAs, £4,000 for Lifetime ISAs and £9,000 for Junior ISAs and Child Trust Funds until 5 April 2031¹².

What counts towards the limit is new money paid in during the tax year. The £20,000 ISA allowance only concerns new money paid into an ISA in the tax year¹³. Interest or growth that builds up inside the ISA does not eat into the allowance, and neither does money that was already in ISAs in earlier years. If you deposit £10,000 one year, you cannot deposit £30,000 the next year to make up for it: allowances do not roll over between tax years¹⁴.

Who can use the allowance is broad. All UK residents aged 18 or over can have a cash ISA or a stocks and shares ISA, and Crown employees serving overseas, or individuals married to such employees, are also eligible⁵. Children become eligible for an adult ISA when they turn 18¹⁵, and under-18s can hold Junior ISAs instead.

The allowance has not always been £20,000, which is worth remembering when reading older guides. In the 2015/2016 tax year the limit was £15,240 across a cash ISA, investment ISA or a combination¹, and the increase to £20,000 came later. The current figure is frozen rather than rising annually, so planning around "next year's bigger allowance" does not work.

Unused allowance is lost, not carried forward

This is the rule that gives the ISA deadline its bite. You cannot carry over unused ISA allowance into the next tax year, and your allowance resets every 6 April⁴. Any unused allowance does not roll over, so you need to use it by 5 April or lose it¹⁶. Which? puts it bluntly: the allowance does not roll over if it is not used, instead you lose it¹⁷.

The loss is permanent and personal. There is no mechanism to reclaim an unused allowance from a past tax year, no form to fill in, and no way to add it to a later year. Someone who used only £5,000 of their allowance in 2026-27 does not start 2027-28 with £35,000: they start with the standard £20,000, exactly the same as everyone else¹⁴. Over several years, unused allowances can add up to a large amount of savings capacity that can never be recovered, which is why the weeks before 5 April see such a rush of activity⁹.

The rule also means the deadline is about paying money in, not about the balance left in the account. What matters is what you subscribed during the tax year. Money withdrawn from a non-flexible ISA and paid back in later in the same year counts again towards the allowance, because the second payment is a new subscription. Flexible ISAs work differently, and the rules on replacing current-year withdrawals were updated in 2025¹⁸; the dedicated page on flexible ISAs covers how that works.

Splitting your allowance across different ISAs

The £20,000 allowance is one pot that can be spread across the different types of ISA. You can split the £20,000 allowance across different types of ISAs, like cash ISAs and stocks and shares ISAs¹⁴. NS&I makes the same point: you can split your £20,000 ISA allowance across multiple types¹⁹. So a saver could put £10,000 into a cash ISA and £10,000 into a stocks and shares ISA, or any other combination, as long as the total paid in across all of them in the tax year is no more than £20,000.

The one structural exception is the Lifetime ISA. Its £4,000 annual limit sits inside the overall £20,000, not alongside it: money paid into a Lifetime ISA uses part of your general ISA allowance¹². The pages on Lifetime ISAs and the ISA allowance cover the detail.

A change in the rules in April 2024 also lets savers split their annual tax-free allowance across multiple ISAs of the same type, even where they could not before⁹. Combined with the ability to open more than one ISA of a type in a year, this means the allowance can now be divided almost however you like, across providers as well as across types. The only hard boundary is the total: £20,000 of new money per tax year, or the reduced cash ISA figure for under-65s from April 2027⁵.

Opening more than one ISA in a tax year

For many years the rule was one ISA of each type per tax year. That changed on 6 April 2024. The ISA rules changed so that you can now open and pay into more than one ISA of the same type in a tax year²⁰, and the regulations were amended to permit an individual to subscribe to more than one ISA account of the same type in a tax year²¹. You can now open and pay into an unlimited number of ISAs in the same tax year²².

In practice this means you could hold cash ISAs with two different providers, paying into each during the same tax year, or subscribe to two stocks and shares ISAs with different platforms. New rules introduced in 2024 mean you can now open more than one ISA of the same type²³, and the reforms also removed the requirement to make a fresh application to open an account already held, and allowed partial transfers of subscriptions made in the current tax year²¹.

The limit that has not changed is the total. However many accounts you spread it across, you still cannot exceed the £20,000 allowance across them²². More accounts mean more to keep track of, and the risk of accidentally over-subscribing rises with each one. Over-subscribed ISAs can lose their tax advantages, a situation covered in detail on the page about invalid subscriptions.

Lifetime ISA and Junior ISA limits

The other ISA types have their own limits, all of which run on the same 6 April to 5 April year. Annual subscription limits will remain at £20,000 for ISAs, £4,000 for Lifetime ISAs and £9,000 for Junior ISAs and Child Trust Funds until 5 April 2031¹². Lifetime ISAs face subscription limits of £4,000 per year, and face certain withdrawal charges for early access²⁴.

The Lifetime ISA also has age rules that create their own deadlines. You must be 18 or over but under 40 to open a Lifetime ISA²⁵, and you can only add savings up to the age of 50⁵. Someone approaching their 40th birthday therefore has a personal deadline to open the account, and someone approaching 50 has a deadline for their final contribution. The government bonus is paid on contributions, which is what makes the £4,000 limit worth using each year; the pages on the Lifetime ISA and the government bonus explain how it works.

Junior ISAs have a £9,000 annual limit, and the money belongs to the child, who cannot access it until 18. Children are only eligible for an adult ISA when they turn 18¹⁵, at which point a Junior ISA can be rolled into an adult account. A child can hold both a Junior ISA and a Child Trust Fund, but the £9,000 limit is shared between them¹². The rules for Junior ISAs and for moving a Child Trust Fund into a Junior ISA are covered in their own pages.

Transfers and Bed and ISA before the deadline

Transfers are the one ISA movement that does not use allowance. The allowance is not affected by transferring money between ISAs, as long as the providers make the transfers and the money is not withdrawn to you first¹³. This is why a transfer must always be done provider to provider: if you take the money out yourself and pay it into a new ISA, that is a fresh subscription and it counts against this year's allowance.

Transfers have their own clock. A stocks and shares ISA transfer should be completed within 30 calendar days under HMRC guidelines⁶, and the regulations require transfers to take place within 30 days of instruction unless an exception applies⁷. There is a sanction for delay in one situation: ISAs lose their tax-advantaged status if they are not transferred within 30 days of the investor receiving notice from the ISA manager²⁶. If a transfer goes wrong, the page on compensation for delayed ISA transfers explains your options, and how to transfer an ISA sets out the process step by step.

The year end is also the traditional time for a "Bed and ISA": selling investments held outside a tax wrapper and repurchasing them inside an ISA, using current-year allowance before it disappears. The mechanics, costs and tax points are covered on the page about moving investments into an ISA. As with any year-end activity, the earlier in March it is started, the more time there is for settlement and for the transfer to complete inside the tax year.

Changes coming to the ISA allowance from April 2027

The biggest change on the horizon affects cash ISAs. The government has published legislation to reduce the cash ISA annual subscription limit, with the change effective from 6 April 2027¹¹. From that date, major changes will come into force that will impact savers with larger nest eggs²⁷, and from April 2027 the amount under-65s can pay into cash ISAs will be cut to £12,000 a year⁵.

Two things do not change. The overall ISA allowance stays at £20,000, so the reduction only bites on the cash element: an under-65 saver could still put £20,000 into ISAs in total from April 2027, but no more than £12,000 of that into cash ISAs, with the rest available for stocks and shares ISAs, Innovative Finance ISAs and Lifetime ISAs. And money already held in a cash ISA keeps its tax-free status: the new limits apply to money paid in from April 2027 onwards²⁷.

The 2025 regulations also updated the rules relating to withdrawals of a current-year ISA subscription from a flexible account¹⁸, which matters around the year end because it governs whether money taken out late in the tax year can be replaced without using allowance. The full detail of the cash ISA reduction, including how the age rules work, is on the page about changes to the cash ISA limit, and the position for people aged 65 and over is on the page about the cash ISA limit for over-65s.

Help to Buy ISA: final saving and bonus dates

The Help to Buy ISA has its own long-stop dates, which work differently from the general ISA deadline. Help to Buy ISAs were available from 1 December 2015²⁹. The scheme was closed to new accounts on 30 November 2019, though existing Help to Buy ISA account holders can continue saving into their accounts, and the government bonus must be claimed by 1 December 2030²⁴.

The bonus is worth up to £3,000, capped at a total of £3,000 on £12,000 of savings³⁰. The scheme's official statistics cover the period December 2015 to 31 March 2023³¹, and the original policy set the closure timetable: the Help to Buy ISA was open for new savers until 30 November 2019, and open to new contributions until 2029³².

For anyone still holding one, the dates that matter are:

• 30 November 2029: the last date to save into an existing Help to Buy ISA²⁴
• 1 December 2030: the last date to claim the government bonus²⁴

Because the bonus is claimed when a first home is bought, the practical deadline for most holders is the completion of a qualifying purchase, not the saving deadline. The full rules, including what happens to accounts that are never used for a purchase, are on the Help to Buy ISA page.

Inheriting a spouse's ISA allowance

One group of people has more allowance than the standard £20,000: widows and widowers. Spouses and civil partners automatically inherit their deceased partner's ISA allowance³³. Since April 2015 it has been possible to pass on ISA savings to a spouse or civil partner without the survivor losing the tax advantages³⁴.

The formal mechanism is called additional permitted subscription. The legislation permits it where an account investor dies on or after 3 December 2014 leaving a surviving spouse or civil partner who subscribes within the permitted period, and the couple were living together at the date of death³⁵. The surviving partner can inherit an additional ISA allowance up to the value of the deceased's ISAs at the date of death²⁰. So a spouse who died with £50,000 in ISAs leaves their partner not just the inherited money but an extra £50,000 of ISA subscription capacity on top of their own annual allowance.

There are practical points to watch. The additional allowance must be used within the permitted period, and not every provider accepts inherited allowances, so the survivor may need to find one that does. Separately, an ISA is normally closed by the provider where it has been 3 years and 1 day since the date of death³⁶. The full process, including how the allowance is claimed and what happens to the ISA itself, is covered on the page about additional permitted subscription and the wider page on what happens to an ISA when someone dies.

Where to get help

If something goes wrong around the deadline, the first stop is the provider. Payments that missed the cut-off, transfers that have not completed, and questions about which tax year a subscription fell into are all things the provider can check against its records. The page on complaining about an ISA provider sets out the complaints route if the provider does not resolve it, including referral to the Financial Ombudsman Service.

For transfers that have gone astray, the pages on how long an ISA transfer takes and compensation for delayed transfers explain the 30-day standard and what to do when it is missed⁶. For questions about whether a payment broke the rules, the page on invalid subscriptions covers when an ISA can lose its tax-free status and how breaches are put right.

Free, impartial guidance is available from MoneyHelper, the government-backed money guidance service, for general questions about ISAs, allowances and the tax year. HMRC's own guidance and the tax-free savings newsletters are the authoritative source for the current year's limits³, and the page on how your ISA is protected explains the FSCS position if a provider fails.