Glossary · UK
What is Junior ISA (JISA)?
A tax-free savings or investment account for under-18s, with its own separate £9,000 annual allowance for 2026/27, which the child gains full control of at 18.
Full Definition
A Junior ISA is a long-term, tax-free savings or investment account for children under 18 who are UK residents, available in both Cash and Stocks and Shares versions (or split between the two). It has its own annual subscription limit of £9,000 for 2026/27, entirely separate from the parents' or any other adult's own £20,000 ISA allowance, and anyone -- parents, grandparents, other relatives or friends -- can contribute, provided the total paid in across all the child's Junior ISAs in the tax year does not exceed the limit. A parent or legal guardian must open the account and acts as the registered contact managing it on the child's behalf, but the money legally belongs to the child from the moment it is paid in. At age 16 the child themselves can take over management of the account, and at 18 the Junior ISA automatically converts into an adult ISA, at which point the funds become fully accessible to the (now adult) child to withdraw or continue saving, with no restriction on how the money is used -- a point some parents weigh carefully, since there is no way to restrict what an 18-year-old spends the accumulated funds on. A child can hold a Junior ISA alongside a separate Child Trust Fund only in limited transfer circumstances (new Child Trust Funds are no longer issued, and existing ones can be transferred into a Junior ISA), and all growth and income within a Junior ISA is entirely free of Income Tax and Capital Gains Tax, both while it remains a Junior ISA and after it converts to an adult ISA.
How Junior ISA (JISA) is calculated
Maximum annual subscription = 9000- 9000
- Junior ISA annual allowance for 2026/27 (GBP), separate from the adult ISA allowance.
Worked example: Paying the full GBP 9,000 a year into a Junior ISA from birth, growing at 5% a year, would build a pot of roughly GBP 127,000 by the child's 18th birthday, entirely tax-free and outside the parents' own ISA allowance.