Who can open an ISA

Opening an ISA is open to almost every adult in the UK, but the exact conditions depend on which type of ISA you want and how old you are. The headline rules are simple: you must be 18 or over to open most adult ISAs, aged 18 to 39 to open a Lifetime ISA, and you need a National Insurance number when you apply. There is no limit on how many ISA accounts you can hold, as long as your total payments each tax year stay within the annual allowance of £20,000¹.

One big change is on the way. From 6 April 2027, the start of the 2027/28 tax year, the amount you can pay into cash ISAs falls to £12,000 a year if you are under 65, while the overall £20,000 allowance stays in place³. Savers aged 65 and over keep the full £20,000 cash limit⁴. The rules on holding several ISAs have also been relaxed: since April 2024 you can open and pay into more than one ISA of the same type in the same tax year⁵.

The basic conditions for opening an ISA

An ISA is not a product in its own right so much as a tax-free wrapper that sits around savings or investments. The legal framework is the Individual Savings Account Regulations 1998, which set out how accounts are opened by approved managers, how subscriptions are made, and how the tax relief works⁹. In practice, the conditions a person has to meet are about age, National Insurance and the type of account, and each provider applies them through its own application process.

For adult ISAs, the core conditions are that you are old enough for the type of account, you have a National Insurance number if you are eligible for one, and you stay within the annual allowance across everything you pay in¹. There is no minimum amount you must save, and no requirement to save regularly. A child's ISA works differently: a Junior ISA can only be opened and managed by the child's parent or guardian, and the application must be made on the basis that the account will be held by an eligible child immediately after opening¹⁰. The rules for looking after a child's savings, including who can operate an account on a child's behalf, are set out in guidance from NS&I¹⁰.

The rules are set at UK level, so they apply the same way in England, Scotland, Wales and Northern Ireland. The underlying legislation extends to the whole of the United Kingdom, and nothing in the conditions for opening an ISA differs between the four nations⁹.

Minimum age: 18 for most ISAs

The minimum age for opening an ISA was harmonised at 18 years, simplifying what had been different age rules for different types of account². That means anyone aged 18 or over can open a cash ISA¹², a stocks and shares ISA or an Innovative Finance ISA, subject to the other conditions.

The Lifetime ISA is the one adult ISA with an upper age limit as well as a lower one. You must be 18 or over but under 40 to open one⁶, which independent guidance describes as needing to be aged between 18 and 39¹³. Once opened, a Lifetime ISA can be held and paid into beyond the age of 40; it is only the opening that is restricted. The government has confirmed that it will remain possible to open a Lifetime ISA until a replacement product becomes available, and existing account holders can continue to save under the current rules indefinitely⁴.

Junior ISAs sit outside the adult age rules entirely. They are opened by a parent or guardian for a child, and the child takes control of the account at 18¹⁰. More detail is in the guide to Junior ISAs.

You need a National Insurance number

When you apply for an ISA, the provider will ask for your National Insurance number. A National Insurance number is what makes sure your National Insurance contributions and tax are recorded against your name only¹⁴. The requirement on providers has been tightened by successive amendments to the ISA regulations: ISA managers must obtain a National Insurance number from all investors who are eligible to have one, when receiving a subscription to an ISA⁸, and earlier regulations required managers to get a National Insurance number on new ISA applications from all investors eligible to have one¹⁵.

Not everyone has, or can have, a National Insurance number, and the rules make allowance for that. An application to open an account that is not a Junior ISA or a Lifetime ISA must contain confirmation, if it is the case, that the applicant does not qualify for a National Insurance number¹⁶. Investors who are not eligible for a number can continue to subscribe to an ISA once they have confirmed their ineligibility to their ISA manager⁸. In other words, the number itself is not the condition; confirming your status one way or the other is.

The dedicated page on National Insurance numbers and ISAs covers the practical side, including what to do if you do not yet have a number when you want to open an account.

The four types of ISA and who each one is for

There are four main types of adult ISA: a cash ISA, a stocks and shares ISA, an Innovative Finance ISA and a Lifetime ISA¹⁷. The Financial Ombudsman Service, which handles complaints about ISAs, lists the same four¹⁸. Alongside them sits the Junior ISA for children, and you can split your annual allowance across the adult types¹⁹.

• Cash ISA: a savings account where the interest is tax free. Open to anyone aged 18 or over¹². See cash ISAs explained.
• Stocks and shares ISA: holds investments such as funds and qualifying shares. Open from 18. Only authorised or recognised funds may be held in one under current law²⁰. See stocks and shares ISAs explained.
• Innovative Finance ISA: holds peer-to-peer loans and similar lending. Open from 18. See Innovative Finance ISAs.
• Lifetime ISA: for saving towards a first home or retirement, with a government bonus. Open only to those aged 18 or over but under 40⁶. See the Lifetime ISA explained.
• Junior ISA: opened and managed by a parent or guardian for a child¹⁰. See Junior ISAs explained.

Each type suits a different purpose, and the choice between them is covered in comparisons such as cash ISA vs stocks and shares ISA and Lifetime ISA or stocks and shares ISA.

ISA allowance: £20,000 a year across all your ISAs

The annual ISA allowance is £20,000 per tax year⁷. This is a single, shared limit: it applies across all your ISAs combined, not £20,000 per account. Whatever you pay into one ISA reduces what you can pay into the others that tax year. The allowance runs with the tax year, from 6 April to 5 April, and unused allowance cannot be carried forward.

You can split the allowance across the four adult types however you like¹⁹. The Lifetime ISA has its own subscription rules within that: you can open and pay into one Lifetime ISA per tax year²¹. The full detail, including how the allowance interacts with transfers, is on the page about the ISA allowance, and the deadline for using each year's allowance is covered in the ISA deadline and the end of the tax year.

Cash ISA limit falling to £12,000 for under-65s

At Autumn Budget 2025 the government announced that, with effect from 6 April 2027, the annual cash ISA limit for those below the age of 65 will be set at £12,000, within the overall annual ISA limit of £20,000²². The change is made by amending the Individual Savings Account Regulations 1998³, and the measure also introduces supporting rules to make sure the limits operate as intended³.

The age test is about the tax year, not the day you pay in. The legislation works on whether a qualifying individual is 64 or under at the end of the year: in any year in which you are 64 or under at the end of that year, the subscription limit for cash ISA accounts is £12,000²³. Guidance puts it the same way: from 6 April 2027, the start of the 2027/28 tax year, you will have a £12,000 cash ISA allowance if you are aged under 65²⁴. In the 2026/27 tax year, before the change, under-65s can still pay up to £20,000 into cash ISAs²⁴.

For savers aged 65 and over, the annual cash ISA limit remains at £20,000²⁵. The government has retained the higher limit in recognition of the need of those approaching retirement to restructure and derisk their investments, and transfers into cash ISAs are allowed for this group²². Entitlement to the higher limit applies from the start of the tax year in which an individual turns 65²⁶.

The cut does not reduce the overall allowance. An under-65 saver can still subscribe £20,000 a year in total; the effect is that anything above £12,000 must go into stocks and shares, Innovative Finance or Lifetime ISAs rather than cash²². Independent guidance notes the same: from April 2027 the amount under-65s can pay into cash ISAs will be cut to £12,000 a year²⁷. The full detail, including the position for over-65s, is on the pages about changes to the cash ISA limit and the cash ISA limit for over-65s.

More than one ISA of the same type: allowed since April 2024

For many years the rule was one ISA of each type per tax year. That changed on 6 April 2024, when regulations came into force permitting an individual to subscribe to more than one ISA account of the same type in a tax year, allowing partial transfers of current-year subscriptions and removing the need to make a fresh application to reopen an account already held⁵. NS&I states the change plainly: the ISA rules changed on 6 April 2024, and you can now open and pay into more than one ISA of the same type in a tax year¹.

There is no specific limit on how many ISAs you can hold overall, and for most types of ISA you can now have, open and pay into multiple accounts of the same type in the same tax year²⁷. Independent guidance confirms you can open and pay into an unlimited number of ISAs in the same tax year, as long as you do not exceed the overall deposit limit²⁸. The constraint is the £20,000 allowance, not the number of accounts: you could open two cash ISAs and contribute to two stocks and shares ISAs, but the combined payments must stay within £20,000²⁹.

The Lifetime ISA is the exception. Individuals can open and pay into one Lifetime ISA per tax year, though they are free to hold multiple Lifetime ISA accounts with different providers from different years²¹. The detail is on the page about paying into more than one ISA in a year.

Transferring an ISA without losing the tax-free status

An ISA transfer allows you to move your savings from one ISA to another without losing your tax-free benefits³⁰. The mechanics matter: the transfer must be arranged between providers, not done by withdrawing the money yourself. If you take money out of an ISA, it loses its tax-free status³¹, and paying it into a new ISA would use up fresh allowance. For most easy access ISAs, transferring through your provider keeps the tax-free benefits and avoids penalties³⁰.

What can move where depends on the type. Funds invested in a stocks and shares ISA can only be transferred to another stocks and shares ISA, while funds in a cash ISA can be transferred to a stocks and shares ISA or to another cash ISA¹⁷. The 2026 draft regulations extend this: for stocks and shares or Innovative Finance accounts, both the current year's subscriptions and previous years' subscriptions may be transferred to a stocks and shares account, an Innovative Finance account, a Lifetime ISA, or a cash account if the investor is 65 or over at the end of the year²³. You can transfer existing cash ISAs and stocks and shares ISAs into a new stocks and shares ISA without affecting your allowance²⁹.

Shares you already hold outside an ISA cannot simply be moved in, because only authorised or recognised funds may be held in a stocks and shares ISA under current law²⁰. The usual route is to sell and repurchase inside the ISA, a process covered in bed and ISA: moving investments into an ISA. The step-by-step process, timescales and what to do if a transfer stalls are on the how to transfer an ISA page.

Help to Buy: ISA: saving and bonus deadlines for existing holders

The Help to Buy: ISA scheme was launched on 1 December 2015, with accounts available through banks and building societies¹⁷. It closed to new accounts on 30 November 2019¹⁷, and the scheme is closed to new applicants³². Nobody can open a Help to Buy: ISA today; if you are saving for a first home and have no existing account, the Lifetime ISA, open to those aged 18 to 39¹³, is the scheme that still pays a government bonus.

Existing holders keep two deadlines. Account holders can continue saving into their Help to Buy: ISAs until 30 November 2029¹⁷, with independent guidance giving November 2029 as the last date to save³². The government bonus must be claimed by 1 December 2030¹⁷. The original scheme design set the same shape: open for new savers until 30 November 2019, with savers able to claim a bonus until the 2030 deadline³³, and the scheme factsheet confirmed accounts would be open to new contributions until 2029³⁴.

Because the bonus is claimed through the conveyancer as part of a property purchase, the practical deadline for most holders is the completion of a qualifying purchase before the scheme's final dates. The full detail is on the Help to Buy ISA page, and the option of moving a Help to Buy ISA into a Lifetime ISA is covered separately.

What happens to an ISA when the holder dies

When an ISA holder dies, the account does not simply vanish, and the tax position of the estate depends on rules that have changed in savers' favour. A surviving spouse or civil partner can now inherit an additional ISA allowance, up to the value of the deceased's ISA at the date of death³⁵. This is known as the additional permitted subscription, and it means the survivor can put extra money into their own ISAs, on top of the usual annual allowance, equal to what was in the deceased's accounts.

Money taken out of an ISA loses its tax-free status³¹, which is why the inherited allowance matters: without it, a surviving spouse who simply received the money would have to re-shelter it within their ordinary £20,000 allowance. The mechanics of claiming, and the position for estates more generally, are covered in what happens to an ISA when someone dies and additional permitted subscription: inheriting a spouse's ISA allowance.

Where protection comes from, and what happens if a provider loses approval

ISAs are offered by ISA managers, and the 1998 Regulations provide for the approval of account managers by the Board, that is HMRC⁹. A provider must hold that approval to offer an ISA, and the 2026 amendments introduce further requirements: ISA managers who do not currently have HMRC's approval to offer a stocks and shares ISA or an Innovative Finance ISA will need to seek approval²⁰. HMRC can also withdraw a manager's approval, for example where the manager has not offered an account within 18 months of being approved².

For a saver, a provider losing approval does not mean losing the money. The savings remain the saver's; what changes is whether the account can continue as an ISA. The usual remedy is a transfer to another approved manager, using the transfer process described above so the tax-free status is preserved. If something goes wrong, a complaint can be taken to the Financial Ombudsman Service, which handles complaints about individual savings accounts¹⁸. The pages on how your ISA is protected and complaining about an ISA provider set out the detail, including the FSCS protection that sits behind deposits and investments.