Junior ISA
Calculator UK (2026/27)

A Junior ISA (JISA) is a long-term tax-free savings or investment account for children under 18. It can only be opened by a parent or legal guardian, but anyone — grandparents, godparents, family friends — can contribute. Every penny that goes in, plus all the interest, dividends, and capital growth it earns, is completely free from UK tax for the rest of the child's life inside the wrapper.

The annual contribution limit for 2026/27 is £9,000 per child. This limit resets every tax year on 6 April and does not roll over — any unused allowance is lost permanently. The £9,000 limit is shared between the Cash JISA and Stocks & Shares JISA if a child holds both. Crucially, the JISA allowance is completely separate from the parent's own £20,000 adult ISA allowance, so paying into a JISA doesn't eat into your own tax-free wrapper.

The money is locked away until the child turns 18. From age 16, the child can manage the account (changing investments, switching providers) but still cannot withdraw any money. On their 18th birthday, the JISA automatically converts into an adult ISA and the child gains full legal control — they can keep the money invested, withdraw some, or take it all.

For nearly all children, a Stocks & Shares JISA is the better choice — and the reason is simply time. A baby has 18 years until they can access the money, which is comfortably long enough to ride out multiple market downturns and capture the long-term return advantage of equities. Over 18 years, the difference between cash at 4% and equities at 7% is roughly 40-50% more money in the final pot.

Cash JISA may make sense if you are starting late (e.g., the child is already 15 or 16) and want to protect the value before they turn 18. For long horizons, the inflation drag on cash is hard to overcome.

Stocks & Shares JISA is the right default for most children. Use a low-cost global index fund — the same kind you would buy in your own ISA. Over 18 years, the historical data is overwhelming: equities have outperformed cash in nearly every long rolling period. The volatility you see along the way is just noise on the way to a much larger pot.

You can hold one of each type simultaneously and split the £9,000 allowance between them in any proportion. You can also transfer a JISA between providers without affecting the annual allowance.

Only a parent or legal guardian can open a JISA, but once it exists, anyone can contribute to it. This makes JISAs an excellent way for grandparents, godparents, aunts, uncles, and family friends to give meaningful long-term gifts that grow over years rather than birthdays.

All contributions count towards the same £9,000 annual limit, regardless of who pays them in. So if Grandma puts in £2,000 and Mum contributes £100/month, the total of £3,200 leaves £5,800 of room for others before the year ends. The JISA provider tracks the total automatically.

JISA gifts are also useful for inheritance tax planning — anything you contribute is treated as a gift from your estate, and after 7 years it falls outside your estate entirely. For grandparents wanting to pass on wealth, regularly funding a grandchild's JISA can be a tax-efficient way to do so while still seeing the money grow during your lifetime.

On the child's 18th birthday, their JISA automatically converts into an adult ISA. The tax-free wrapper continues — there is no loss of the tax benefits — and the funds remain invested in exactly the same way. The only thing that changes is who controls the account: parents lose all access, and the now-adult child has full legal ownership.

From this moment, the child can do whatever they like with the money. They can leave it invested for the long term (the best option for most), withdraw some for university or travel, or take it all out. There is nothing legally requiring them to make sensible decisions, which is why financial education in the years leading up to 18 matters.

If your child plans to go to university, a JISA pot can fund living costs without needing the maintenance loan — a substantial financial advantage. If they plan to buy a home in their 20s, the JISA money could become the foundation of a deposit (potentially transferred into a Lifetime ISA at 18 to capture the 25% bonus). For pure long-term wealth building, leaving it invested for another 40-50 years inside the adult ISA wrapper produces extraordinary results.