Does unused ISA allowance roll over?

No. Unused ISA allowance does not roll over. If you do not use all of it by the end of the tax year on 5 April, the unused part is gone, and it is not added to the following year's allowance. NS&I puts it plainly: "Your ISA allowances do not roll over, so if you deposit £10,000 one year, you cannot deposit £30,000 the next year to make up the difference."¹

What happens instead is a reset. Your allowance renews on 6 April, the first day of the new tax year, at the standard amount for that year, and everyone gets the same fresh start regardless of what they did or did not use the year before.²

The money already inside your ISA is a different matter. Only the unused allowance is lost, not the savings or investments themselves. Money held in an ISA keeps its tax-free status year after year, and growth inside a stocks and shares ISA does not use up allowance.⁴

Unused ISA allowance does not roll over

The rule is the same wherever you look, and it is worth being clear about what it means in practice. An ISA allowance is described by providers as a use it or lose it allowance: you cannot carry any of it over into the next tax year.⁸ If you have not used all of your allowance, it cannot be rolled over, and you get a fresh allowance once each tax year begins.⁹

That has a consequence people often miss. A year in which you pay nothing into an ISA is not a year you can make up later. The allowance for that year simply expires.⁵ There is no mechanism for banking it, and no application form that restores it.

The same rule applies to Junior ISAs. The allowance resets at the beginning of each tax year, and if it is not used in full by the end of the tax year, the unused portion cannot be carried over.¹⁰ You can read more about how that works on Junior ISAs explained.

What is not lost is the tax shelter itself. An ISA is not a one-year product. Once money is inside, it stays inside the tax-free wrapper, and the fact that you did not use your allowance in a given year has no effect on money you subscribed in earlier years.⁴

Your allowance resets every 6 April

The tax year runs from 6 April to 5 April, and the allowance resets on 6 April.¹¹ That date is fixed, and it does not move for weekends or bank holidays. Providers describe it the same way: the allowance renews on 6 April each year and does not carry over.¹²

The reset is automatic. You do not need to apply for a new allowance, and you do not need to do anything to trigger it. If you want to use the full allowance as soon as it resets on 6 April, you can.¹³

One practical point sits alongside the reset. Some providers require an ISA to be renewed before you pay in again if you did not use any of your allowance for an entire tax year.¹⁴ That is an administrative step with the provider, not a change to the allowance itself, but it is worth knowing if you have an old ISA you have not touched for a while.

Use it by 5 April or lose it

The tax year ends on 5 April every year, and you must use all of your allowance by that date or lose it.⁶ Any unused allowance does not roll over, so the deadline is real rather than a formality.¹⁵

The last few days before the deadline are the point at which this matters most. Money paid in on 4 or 5 April counts against that year's allowance, and money paid in on 6 April counts against the new one. There is no grace period in between.

The deadline also shapes how people use the allowance across the year. Because the allowance resets rather than accumulates, spreading payments across the year and using the full amount each year produces a different result from saving up and paying in a lump sum later. The allowance you did not use in the year you saved is not waiting for you.

If you are working out how much of the current year's allowance is left, the ISA allowance page sets out the figure and how it is shared, and the ISA deadline and the end of the tax year covers what happens in the final weeks.

Cash ISAs and stocks and shares ISAs follow the same rule

The no-carry-over rule is not specific to one type of ISA. It applies to cash ISAs, stocks and shares ISAs, innovative finance ISAs and Lifetime ISAs alike, because the allowance is a single pot shared across them.¹⁶ You can split your allowance in any proportion between a stocks and shares ISA and a cash ISA, with one allowance in total.¹⁷

What differs between the types is not whether unused allowance carries over, but what you can hold and how money moves between them.

The Lifetime ISA has its own annual limit in addition to the overall ISA allowance, and money transferred in from other ISAs counts towards that Lifetime ISA limit even though it does not count towards the overall ISA allowance.²² The Lifetime ISA explained page covers how that interacts with the rest of your allowance.

You can hold more than one stocks and shares ISA, cash ISA or innovative finance ISA, but the total you pay in across all of them still cannot exceed the overall ISA allowance.²³ Holding several accounts does not create extra allowance, and it does not create any carry-over either.

Transferring an ISA: what happens to this year's allowance

Transferring an ISA is not the same as paying in, and it does not use up allowance. When you transfer an ISA, it does not use up your ISA allowance.⁷ Transferring an ISA from a previous tax year does not affect your allowance for the current tax year, provided it is done through the new provider's ISA transfer process.²⁴

The distinction that matters is between money from previous tax years and money paid in during the current one.

• Previous tax years' money: does not count towards the current year's allowance at all when transferred, and can normally be moved in full or in part.²⁵
• Current tax year's money: counts as a subscription, and generally has to be moved in full rather than in part.²⁷

If you paid £1,000 into a cash ISA and then transferred it to a stocks and shares ISA in the same tax year, you would still have used up only £1,000 of that year's allowance.⁸ The transfer moves the money; it does not create a second subscription.

Partial transfers and the current year rule

Money saved in previous years can usually be transferred in full or in part.²⁶ Money paid in during the current tax year is different: you cannot partially transfer money deposited in the current tax year, and the full subscription has to be moved.²⁷ Nationwide states the same rule for transfers into its ISAs: all money paid into a non-Nationwide ISA in the current tax year must be transferred, and you cannot transfer just part of it.¹⁴

There has been movement on this. Providers may allow partial transfers of current tax year ISA subscriptions from 6 April 2024, but not all do.²⁸ Where a provider does not offer it, the full current year subscription has to move together.

The 30-day limit on fixed rate cash ISAs

Some fixed rate cash ISAs restrict when transfers in are accepted. One fixed rate account accepts transfers of used ISA allowances on account opening only where the funds are accessible within 14 days and received within 30 days of account opening, and after that date no transfers of used ISA allowances are permitted.²⁹ Another accepts transfers in from flexible and non-flexible cash ISAs, requires the current tax year allowance to be transferred in full, allows previous years' savings to be transferred in part or in full, does not permit transfers from stocks and shares ISAs, and processes transfers by cheque with up to 15 working days to complete.³⁰

The 30-day limit is not universal. It was removed for fixed cash ISAs opened before 2 June 2025 at one provider, which states that the limit does not apply to accounts opened before that date.³¹ Because the terms differ by account and by opening date, the specific account terms are the place to check.³²

If you are moving money between accounts, how to transfer an ISA walks through the process, and does transferring an ISA use my allowance? deals with the allowance question on its own.

Where the rules can catch you out

A few situations cause more confusion than the basic rule.

Cancelling an ISA opened near the deadline. Cooling off rights let you cancel a product shortly after opening it, but cancelling does not normally restore the allowance for the tax year in which the money was paid in. If you cancel after the tax year has ended, the subscription is treated as having been made in the year it was paid in.³³ The cancelling an ISA page covers how cooling off interacts with deadlines.

Flexible ISAs. A flexible ISA lets you take money out and put it back in the same tax year without using more allowance. A stocks and shares ISA that is not flexible does not work that way, and withdrawals do not restore allowance within the same tax year.³⁴ If replacing money you have taken out matters to you, flexible ISAs explains the difference.

Transferring shares in. If you transfer shares into an ISA rather than cash, the value cannot exceed what you have left of your allowance for that year.³⁵

Interest earned outside an ISA. Interest on savings held outside an ISA can affect your tax position, but it does not reduce your ISA allowance.⁴

What protects you, and where it stops

The rules that govern ISAs are set out in legislation, and the transfer rules in particular have been amended over time. Regulation 21 provides the rules for the transfer of ISAs, and an amendment in 2014 revoked the provision that had prohibited transfers from stocks and shares ISAs to cash ISAs, permitting them from 1 July 2014.²⁰ That is why a stocks and shares ISA can now be moved into a cash ISA, which was not always the case.

The protection that matters most to a saver is the tax treatment itself. Money in an ISA is not subject to UK income tax or capital gains tax, and that protection does not expire when the tax year ends. What expires is your ability to add new money under that year's allowance.

Where the protection stops is at the allowance. There is no mechanism to appeal a lost allowance, and no provider can restore it. If a subscription breaks the rules, the invalid subscriptions page explains what happens. If you have a problem with a provider over a transfer or an account, complaining about an ISA provider sets out the route, which includes the Financial Ombudsman Service. MoneyHelper offers free, impartial guidance on ISAs and savings if you want to talk the options through with someone independent.