Junior ISAs Explained: Locking Away £9,000 a Year for Your Child

A Junior ISA (JISA) is one of the simplest tax-efficient accounts available to parents, but the annual allowance is large enough - and the access rules different enough from an adult ISA - that it’s worth understanding properly before you open one.

The basics

• Available for any UK-resident child under 18 who doesn’t already have a Child Trust Fund.
• £9,000 a year can be paid in, from parents, grandparents, or anyone else, combined across all JISAs the child holds.
• Choose a Cash JISA, a Stocks & Shares JISA, or split the allowance between both.
• A parent or legal guardian opens the account and acts as the registered contact, but the money legally belongs to the child.

The access rules are very different from a Junior SIPP

Unlike a Junior SIPP (see our dedicated article in the Pensions series), which stays locked until the child reaches retirement age decades later, a JISA converts automatically into a normal adult ISA when the child turns 18, and the money is then entirely theirs to access and spend however they choose - the parent has no further say at that point. This is worth planning around: a JISA is not a mechanism for controlling how the money is eventually used.

Cash JISA vs Stocks & Shares JISA

• Cash JISA: works like a Cash ISA - capital is secure, and interest is tax-free. As of mid-2026, some providers (including NS&I) have offered Junior ISA rates around 3.7% variable.
• Stocks & Shares JISA: invests the money, with the potential for higher growth over a long time horizon but with investment risk - since most JISAs run for many years before the child turns 18, this is where the long time horizon can work strongly in the investor’s favour, similar to the logic behind a Junior SIPP.

Why the long time horizon matters so much

A JISA opened at birth has 18 years to grow before the child gains access - a genuinely long investment horizon by most standards, second only to a Junior SIPP’s multi-decade timeline. For money that won’t be needed for well over a decade, this is one of the strongest arguments for choosing a Stocks & Shares JISA over cash, though it comes with the acknowledgement that investment values can fall as well as rise over any given period.

What to consider before opening one

• You can’t withdraw the money yourself once it’s in, even in a financial emergency - JISA funds are locked to the child until 18, with extremely limited exceptions (such as terminal illness).
• The child gains full control at 18, regardless of whether you think they’re ready to manage that sum responsibly - there’s no mechanism to delay or stagger this within the JISA rules themselves.
• Grandparents and other family members can contribute too, making a JISA a common destination for family gifts instead of, or alongside, cash presents.

How it compares to a Junior SIPP

A JISA and Junior SIPP solve different problems. A JISA gives a young adult a lump sum they can use for anything - university costs, a house deposit, a first car - at 18, and for those planning to buy their first home, moving some of that lump sum into a Lifetime ISA once they’re old enough can add a further 25% government bonus on top of what’s already been saved. A Junior SIPP is locked away for retirement, decades further out, with an automatic 20% government top-up on contributions rather than tax-free growth alone. Many families use both, splitting contributions between the two depending on what they’re hoping to help the child achieve and when.

The bottom line

A Junior ISA is a simple, tax-efficient way to build a lump sum for a child, but be clear-eyed that the money becomes entirely theirs at 18 with no further parental control - plan your contributions and expectations around that reality from the outset.