What happens to a Junior ISA at 18? Adult ISA rules

What happens to a Junior ISA at 18?

When a child turns 18, their Junior ISA automatically turns into an adult ISA, and they can take out any money in their Junior ISAs. Until then the money normally cannot be taken out, and it cannot be transferred between a Junior ISA and an adult ISA.

The short answer

At 18, a Junior ISA turns into an adult ISA automatically, and the child can take out any money in their Junior ISAs.

Before 18, the money cannot be taken out, with exceptions such as terminal illness, and money cannot be transferred between a Junior ISA and an adult ISA.

The adult ISA follows the adult rules: a £20,000 allowance for 2026/27 and a £20,000 Cash ISA limit at every age, after a planned cut to £12,000 was cancelled in the Budget on 28 October 2026.

If a child lacks the mental capacity to manage the account at 18, someone must apply to the Court of Protection for a financial deputyship order.

What happens to a Junior ISA when the child turns 18?

A Junior ISA turns into an adult ISA automatically when the child turns 18, and the child can take out any money in it. gov.uk says: “When your child turns 18 they can take out any money in their Junior ISAs. Junior ISAs automatically turn into an adult ISA when the child turns 18.”

The money in a Junior ISA belongs to the child, so at 18 it is theirs to take out, and any money left in the account carries on in the adult ISA, under the adult ISA rules below. See Junior ISAs for the full Junior ISA rules.

A Junior ISA at 18, at a glance

What happens to the Junior ISA: Becomes an adult ISA; Automatically, when the child turns 18
Money in the account: Can be taken out; Any of it, once the child is 18
Adult ISA allowance, 2026/27: £20,000; The Junior ISA limit is £9,000
Cash ISA limit from 6 April 2027: £20,000; Planned cut to £12,000 cancelled

What changes at 16 and 18?

The rules change at 16 and again at 18. The table sets out what gov.uk says at each stage.

Age	What gov.uk says
Under 16	Only parents or a guardian with parental responsibility can open a Junior ISA for the child. The registered contact manages the account, and the money cannot be taken out.
16 and 17	The child can open their own Junior ISA, and can become the registered contact. The money still cannot be taken out.
18	The child can take out any money in their Junior ISAs, and the Junior ISAs turn into an adult ISA.

Money in a Junior ISA cannot be taken out until the child turns 18, though there are exceptions, such as terminal illness. gov.uk also says money cannot be transferred between a Junior ISA and an adult ISA. At 18 no transfer is needed, because the Junior ISA turns into an adult ISA itself. See how an ISA transfer works for moving an adult ISA to another provider. A Child Trust Fund, the older scheme for children born between 1 September 2002 and 2 January 2011, works differently at 18: see what happens to a Child Trust Fund at 18.

What if the child cannot manage the account at 18?

gov.uk says that if a child lacks the mental capacity to manage their account when they turn 18, someone must apply to the Court of Protection for a financial deputyship order.

In Scotland, applications are made to the Office of the Public Guardian in Scotland. In Northern Ireland, they are made to the Office of Care and Protection.

What are the adult ISA rules from 18?

An adult ISA has a minimum age of 18. See ISA age limits for the age rule for every type of ISA. The overall allowance for adult ISAs is £20,000 for 2026/27, compared with £9,000 for Junior ISAs. See what an ISA is for how the types differ.

The Cash ISA limit stays £20,000 at every age, so someone who has just turned 18 can put all of their allowance into a Cash ISA. A planned cut to £12,000 for savers under 65 was cancelled in the Budget on 28 October 2026. See the Cash ISA limit.

Is the money at risk after 18?

If the Junior ISA is a Stocks and Shares Junior ISA, yes. It holds investments, so capital is at risk: the value can fall as well as rise, and the child may get back less than was paid in. The same applies once it has turned into an adult ISA. Because the money normally cannot be taken out before 18, its value at that point is not guaranteed.

Questions people ask

Does a Junior ISA turn into an adult ISA at 18?

Yes. gov.uk says Junior ISAs automatically turn into an adult ISA when the child turns 18.

Can a child take the money out of a Junior ISA at 18?

Yes. gov.uk says that when a child turns 18 they can take out any money in their Junior ISAs. Until then the money cannot be taken out, with exceptions such as terminal illness.

Can a 16 or 17 year old manage their own Junior ISA?

A child of 16 or over can become the registered contact for their Junior ISAs, and children aged 16 and 17 can open their own Junior ISA. The money still cannot be taken out until they are 18.

What if a child cannot manage their account at 18?

gov.uk says that if a child lacks the mental capacity to manage their account when they turn 18, someone must apply to the Court of Protection for a financial deputyship order. In Scotland, applications are made to the Office of the Public Guardian in Scotland, and in Northern Ireland to the Office of Care and Protection.

What is the ISA allowance once a child turns 18?

An adult ISA has a minimum age of 18 and an allowance of £20,000 for 2026/27. The Cash ISA limit is £20,000 at every age, within that allowance. See ISA age limits and the Cash ISA limit.

Keep reading

Junior ISA for grandchildren: how grandparents can pay in Anyone can pay into a Junior ISA, up to £9,000 in total for 2026/27. How grandparents can pay in, the £100 interest rule and Inheritance Tax gift rules.

ISA age limits: who can open each type of ISA You must be 18 to open a Cash, Stocks and Shares, Innovative Finance or Lifetime ISA. See each type's age limit and why age no longer affects the Cash ISA limit.

ISA allowance and limit 2026/27: how the £20,000 splits The 2026/27 ISA allowance and limit is £20,000, shared across cash, Stocks and Shares, innovative finance and Lifetime ISAs. How it splits, and what changes.

How does an ISA transfer work? Move an ISA by asking your new provider to transfer it, not by withdrawing the cash. How transfers work, how long they take, and what changes in 2027.

What is an ISA? An ISA is a tax-free wrapper for savings or investments, with a £20,000 yearly allowance. The types, who can open one, and what's changing in 2027.

Cash ISA limit: the £12,000 cut is cancelled The Budget on 28 October 2026 cancelled the £12,000 Cash ISA limit for under-65s. The limit stays £20,000 at every age. What was planned and what is next.