Guide · 4 minute read · Updated 10 Jul 2026

Junior ISAs explained: allowance, rules and how they work

A Junior ISA is a tax-free savings or investment account for a child, with an allowance of £9,000 a year. Anyone can pay in, the child cannot touch it until 18, and given enough years the growth can be the biggest part of the pot.

The £9,000 allowance and who can pay in

In 2026/27 you can put up to £9,000 a year into a child's Junior ISA (JISA). That is separate from your own £20,000 adult allowance, so paying into a child's JISA does not reduce what you can save for yourself. The allowance resets each tax year and any unused part is lost, not carried forward.

Only a parent or legal guardian can open the account and act as its registered manager, but anyone can contribute: grandparents, other relatives, family friends. Everything inside grows free of UK tax on interest, dividends and gains, and none of it counts against the paying adult's own ISA allowance.

Cash or stocks and shares

Like adult ISAs, a JISA comes in two flavours. A cash JISA earns tax-free interest and never falls in value, which suits money that might be needed sooner or a saver who wants certainty. A stocks and shares JISA invests in funds and shares, with the ups and downs that brings, but far more growth potential over a long horizon.

Because a JISA runs until the child turns 18, the time horizon is usually long, often the full 18 years from birth. That is exactly the setting where investing tends to beat cash, so many parents choose a stocks and shares JISA for a newborn and only lean towards cash as 18 approaches. A child can hold one cash JISA and one stocks and shares JISA at the same time, within the single £9,000 limit.

When the child gets control, and the money

Two ages matter. At 16, the child can take over managing the account: they become the registered contact and can make investment decisions, though they still cannot withdraw. At 18, the JISA automatically becomes an adult ISA in their name, and the money is fully theirs to spend, keep invested or move.

There is no way to restrict what they do with it at 18, which is worth thinking about before you build a large pot. The JISA replaced the Child Trust Fund (CTF) for children born from 2011, and no child can hold both. If your child has an old CTF, you can transfer it into a JISA, which often has lower charges and more choice, and doing so gives the full £9,000 JISA allowance regardless of the CTF.

What compounding does over 18 years

The long lock-in is the JISA's superpower. Pay in £100 a month from birth and you contribute £21,600 over 18 years. At a long-run growth assumption of 5% a year after charges, that pot could grow to around £35,000, so roughly £13,000 of it is growth the child never had to earn. See how different amounts and rates play out with the compound interest calculator.

Push it to the full £9,000 a year and the numbers become life-changing, though few families can manage that. The point stands at any level: starting early and letting tax-free growth compound for the best part of two decades does most of the work, far more than trying to save large amounts in the final few years.

Common questions

How much can I put in a Junior ISA in 2026/27?

Up to £9,000 per child in the 2026/27 tax year, across a cash JISA, a stocks and shares JISA, or a mix of both. The allowance is separate from your own £20,000 adult ISA allowance and any unused part is lost at the end of the tax year.

When can a child access their Junior ISA?

The child can take over managing the account at 16 but cannot withdraw money until they turn 18. At 18 the Junior ISA automatically becomes an adult ISA in their name and the money is entirely theirs to use as they wish.

Who can open and pay into a Junior ISA?

Only a parent or legal guardian can open the account and manage it, but anyone can pay in, including grandparents and family friends. Contributions do not count towards the paying adult's own ISA allowance.

Can a child have a Junior ISA and a Child Trust Fund?

No, a child cannot hold both at once. If they have an old Child Trust Fund you can transfer it into a Junior ISA, which usually offers lower charges and more choice, and the child still gets the full £9,000 Junior ISA allowance.

Guidance and education, not regulated financial advice.