Answers · UK 2025/26
What happens to a Junior ISA when my child turns 18?
The Junior ISA automatically converts into an adult ISA on the child's 18th birthday, and they gain full control of the money -- parents lose all say over withdrawals from that point, even though they were the one managing the account throughout childhood.
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A Junior ISA (JISA) is a tax-free savings or investment account for under-18s, with an annual subscription limit of £9,000 for 2026/27, managed by a parent or guardian as the 'registered contact' on the child's behalf. Money paid in cannot normally be withdrawn until the child turns 18, which is what distinguishes a JISA from an adult ISA that allows access at any time. On the child's 18th birthday, two things happen. First, the account automatically converts into an adult ISA of the equivalent type -- a Junior Cash ISA becomes an adult Cash ISA, and a Junior Stocks and Shares ISA becomes an adult Stocks and Shares ISA -- without any tax consequences and without needing to sell and rebuy investments. Second, and often surprisingly for parents, legal control of the account passes entirely to the child at that point. The 18-year-old can withdraw all or part of the money, close the account, transfer it elsewhere, or continue saving into it, with no further input needed from the parent who set it up and contributed to it for years. Between age 16 and 18, a young person can actually open and manage their own adult Cash ISA alongside their existing Junior ISA (since the minimum age for a Cash ISA is 16, while a Stocks and Shares ISA requires being 18), giving some 16 and 17-year-olds two active ISA allowances at once for a couple of years -- their JISA allowance and a separate adult Cash ISA allowance. Because control transfers automatically and completely at 18 regardless of how the money is intended to be used (for example, university costs, a first car, or a house deposit), some families choose to keep an equivalent amount in a parent's own ISA instead of a JISA if they want to retain more control over the timing and purpose of withdrawal, accepting the trade-off of losing the child's own separate tax-free allowance. Use the ISA calculator to compare Junior ISA and adult ISA growth over time.
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This answer is informational only and does not constitute financial, tax or legal advice. Figures are for the 2025/26 UK tax year. See our methodology and sources.