What Happens to a Junior ISA When Your Child Turns 16? (2026/27)
The often-missed Junior ISA rule: at 16, the child can take over managing the account and apply for their own adult Cash ISA too, even though they can't withdraw the money until 18. What this means for parents in 2026/27.
Control Transfers at 16 — Access Still Waits Until 18
A Junior ISA is normally opened and managed by a parent or guardian acting as the "registered contact," but this changes automatically at 16: the child themselves gains the right to manage the account, including choosing the provider and how the money is invested (for a Junior Stocks & Shares ISA) or which Cash Junior ISA offers the best rate. What doesn't change at 16 is access to the money — despite now controlling the account, the 16 or 17-year-old still can't withdraw funds until they turn 18, when the account converts automatically.
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The detail many families miss is that a 16 or 17-year-old is entitled to both a Junior ISA allowance and a full adult Cash ISA allowance in the same tax year, because the adult ISA age threshold for a Cash ISA is 16, two years earlier than the age-18 threshold that applies more broadly to opening most other adult accounts and to Stocks & Shares ISAs. This means a family with the means to do so can, in principle, shelter money across two separate ISA allowances for a 16 or 17-year-old in the same tax year — the Junior ISA allowance and a full adult Cash ISA allowance — something that isn't possible once the child turns 18 and the Junior ISA converts, collapsing back to a single allowance.
What Happens at 18
When the child turns 18, the Junior ISA automatically converts into an adult ISA, and the now-adult account holder gains full, unrestricted access to the funds, including the choice to withdraw some or all of it, transfer it, or continue investing. Parents planning long-term savings for a child should be aware that once this conversion happens, the money is legally the young adult's to use as they choose — there's no mechanism to keep it locked beyond 18 or to direct how it's spent.
Contributions Continue After 16
Taking over management of the account at 16 doesn't stop further contributions — parents, grandparents or anyone else can continue paying into the Junior ISA up to the annual Junior ISA allowance right through to the child's 18th birthday, alongside the account holder's own management of how the money already in the account is invested or held.
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- Understand that a 16-year-old gains management control of a Junior ISA, but not access, until 18
- Consider whether opening an adult Cash ISA for a 16 or 17-year-old makes sense alongside the Junior ISA
- Plan for the Junior ISA converting automatically to an adult ISA, with full access, at 18
- Keep contributing to the Junior ISA up to the annual allowance if that fits your family's savings plan
This article is general information, not financial or tax advice. Figures use 2026/27 UK ISA allowances and rules.
Frequently asked questions
Can a 16-year-old take control of their own Junior ISA?
Yes — from age 16, a child automatically gains the right to manage their own Junior ISA account (previously run by a parent or guardian as 'registered contact'), including choosing where it's held and how it's invested, even though they still can't withdraw the money until they turn 18.
Does a 16-year-old with a Junior ISA also get their own adult ISA allowance?
Yes — this is a widely underused feature of the rules: a 16 or 17-year-old can hold a Junior ISA and also open and pay into their own adult Cash ISA in the same tax year, in effect giving access to two separate ISA allowances at once.
Can a 16-year-old withdraw money from their adult Cash ISA before turning 18?
Yes — unlike a Junior ISA, which is locked until 18, an adult Cash ISA opened at 16 or 17 works like any other adult ISA, meaning the account holder (the teenager) can generally access the money, subject to the specific provider's terms.
What happens to the Junior ISA when the child turns 18?
At 18, the Junior ISA automatically converts into an adult ISA and the funds become fully accessible to the (now adult) account holder, who gains complete control over the money, including the option to withdraw or continue investing it as they see fit.
Can parents still contribute to a Junior ISA once the child is 16 and managing it themselves?
Yes — anyone can still contribute to the Junior ISA up to the annual Junior ISA allowance, even after the child has taken over day-to-day management of the account at 16; taking control of the account isn't the same as the account closing to further contributions.
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