Junior ISA
Growth Calculator
See how your child’s savings could grow over 18 years. Enter your contributions and estimated return rate to project your JISA’s future value — completely free.
Your JISA Details
Fill in the details below to project your child’s Junior ISA value at age 18.
Enter your child’s details and contribution plan, then hit Calculate.
| Age | Year End Value | Total Contrib. | Growth |
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Junior ISA key facts
Annual Allowance
The maximum you can save into a Junior ISA each tax year (2024/25). That’s £750 per month.
Locked Until 18
Funds are locked until your child turns 18, when the JISA automatically converts to an adult ISA.
Tax-Free Growth
All interest, dividends and capital gains inside a JISA are completely free from UK tax.
Who Can Open One
Any UK-resident child under 18 who doesn’t have a Child Trust Fund can have a Junior ISA.
Tips to maximise your JISA
Start as Early as Possible
Compound growth is most powerful over long time horizons. Opening a JISA at birth versus age 5 can add tens of thousands of pounds to the final value, even with the same monthly contribution.
Use the Full Allowance
The £9,000 annual allowance cannot be carried over. Consider setting a direct debit for £750/month and encouraging family members to contribute at birthdays and Christmas instead of buying gifts.
Stocks & Shares vs Cash
Over 18 years, a Stocks & Shares JISA has historically delivered significantly higher returns than a Cash JISA, despite short-term volatility. Consider your child’s time horizon and your own risk tolerance.
Gift Aid & Lump Sums
Tax rebates, inheritance gifts, and windfalls can be paid into a JISA in a single lump sum (up to the annual limit). A single £1,000 lump sum at birth can be worth over £3,000 by age 18 at 7% growth.
Switch Providers Freely
You can transfer a Junior ISA to a different provider at any time without losing your allowance or tax benefits. Compare providers annually — fees and interest rates vary widely and compound over time.
Frequently asked questions
The Junior ISA annual allowance for 2024/25 is £9,000 per tax year. This resets on 6 April each year and cannot be carried forward. You can split this between a Cash JISA and a Stocks & Shares JISA for the same child, as long as the total doesn’t exceed £9,000.
When your child turns 18, the Junior ISA automatically matures and converts to an adult ISA. Your child then takes full control of the account and can withdraw the money, keep it invested, or transfer it to a different provider. No tax is payable on any of the growth accumulated inside the account.
Yes. Anyone can make contributions into a child’s Junior ISA — grandparents, godparents, friends and other family members. However, only a parent or legal guardian can open the account and manage it. Total contributions from all sources must not exceed £9,000 in a tax year.
A Cash JISA works like a savings account, paying interest at a fixed or variable rate. A Stocks & Shares JISA invests in equities, bonds and funds, offering higher potential returns but with more risk. Over long periods (10+ years), Stocks & Shares JISAs have historically outperformed cash significantly, but the value can fall as well as rise.
No — funds in a Junior ISA are locked away until the child turns 18. The only exceptions are terminal illness of the child, or the death of the child. This lock-in is actually a feature for long-term saving, as it prevents the money being spent before the child is old enough to benefit from it.
Children born between 1 September 2002 and 2 January 2011 may have a Child Trust Fund. You cannot hold both a CTF and a Junior ISA simultaneously — but since April 2015, you can transfer a Child Trust Fund into a Junior ISA. Many providers accept CTF transfers, which can offer better rates and more investment choice.