Answers · UK 2025/26

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

When a child with a Junior ISA turns 18, the account automatically converts into a standard adult ISA (Cash or Stocks and Shares, matching the type held), and the child gains full legal control over it, including the right to withdraw all the money -- even if a parent originally opened and funded the account.

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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, that automatically becomes the child's own adult ISA on their 18th birthday. **Automatic conversion, not a new account** On the child's 18th birthday, the Junior ISA automatically becomes a standard 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. No new account needs to be opened, and the ISA-tax-free status of the existing funds is preserved without triggering any tax charge on the transition itself. **Full legal control passes to the (now adult) child** This is the aspect that surprises many parents: once the child turns 18, they have complete legal control over the account, including the right to withdraw the entire balance and spend it however they wish -- there is no mechanism for a parent to restrict access or veto withdrawals, regardless of who originally contributed the money. **The "gap" between 16 and 18** A nuance worth understanding: a 16 or 17 year old can ALREADY open their own adult Cash ISA (using the full £20,000 adult allowance) alongside continuing to hold a Junior ISA, meaning some 16-17 year olds effectively have access to both a JISA and an adult Cash ISA allowance simultaneously during this two-year window, though adult Stocks and Shares ISAs and Lifetime ISAs still require the account holder to be 18. **Worked example** Parents open a Junior Stocks and Shares ISA for their daughter at birth and contribute regularly, building a pot worth £35,000 by her 18th birthday. On that birthday, the account automatically becomes her own adult Stocks and Shares ISA. She now has full legal right to withdraw and spend the money as she chooses -- for university costs, a car, or anything else -- regardless of her parents' original intentions for the fund (e.g. hoping it would go towards a house deposit). **Managing the transition** Because 18-year-olds gain unrestricted access, many families use the approaching 18th birthday as a prompt to have an open conversation about financial goals and planning (house deposit, further study, starting a Lifetime ISA to get the 25% government bonus for a first home) before the money becomes fully accessible. **No withdrawals before 18 (with limited exceptions)** Generally, Junior ISA funds cannot be withdrawn before the child turns 18, except in cases of terminal illness or death of the child, ensuring the savings are genuinely locked away for their benefit until adulthood.