What is a Junior ISA?
A Junior ISA (JISA) is a tax-free savings or investment account for children under 18, available to UK residents. Any growth — whether from interest, dividends, or investment gains — is completely free from income tax and capital gains tax. The money belongs to the child but is locked away until they turn 18, at which point it converts automatically to an adult ISA.
There are two types: a Junior Cash ISA (holds cash, earns interest) and a Junior Stocks and Shares ISA (invests in funds, shares, or other assets). You can hold one of each simultaneously, but contributions across both cannot exceed the annual allowance.
The annual Junior ISA allowance is £9,000 per child for the 2025/26 tax year. This is the combined limit across both a Junior Cash ISA and a Junior Stocks and Shares ISA. The allowance resets on 6 April each year — unused allowance cannot be carried forward.
Junior Cash ISA vs Junior Stocks and Shares ISA
The key difference is risk and return. A Junior Cash ISA holds your money as cash and pays a fixed or variable interest rate — your capital is safe but returns are limited by prevailing interest rates. A Junior Stocks and Shares ISA invests your money in the stock market — the value can fall as well as rise, but over the long periods typical of childhood savings, has historically produced significantly higher returns.
Given the 18-year horizon of a Junior ISA opened at birth, most financial guidance suggests that a Stocks and Shares ISA is likely to outperform a Cash ISA over that period — though past performance is not a guarantee of future returns, and capital is at risk.
How much could your child have by 18?
The table below shows projected values at age 18 for different monthly contribution amounts, assuming an 8% annual return — broadly in line with long-run global stock market averages. These are projections, not guarantees.
| Monthly contribution | Who this might be | Value at age 18 (8% p.a.) |
|---|---|---|
| £25/month | Parent alone | £13,367 |
| £50/month | Half of child benefit | £26,734 |
| £100/month | Parent + grandparents | £53,468 |
| £200/month | Family network | £106,936 |
| £750/month | Full allowance (£9,000/yr) | £401,010 |
The figures above assume investing from birth to age 18. Even modest regular contributions, started early and left to compound, build to meaningful sums. The key variable — more than contribution size — is how early you start.
Starting at birth with £50/month builds to £26,734 by age 18. Starting at age 5 with the same contribution builds to £17,474. A 5-year delay costs £9,260 in final value — on identical monthly contributions. That gap grows dramatically at higher contribution levels.
Who can open a Junior ISA?
Only a parent or legal guardian can open a Junior ISA for a child. The child must be under 18 and a UK resident. Once the account is open, anyone can contribute — grandparents, godparents, aunts, uncles, family friends. All contributions count toward the £9,000 annual limit regardless of who makes them.
Children aged 16 or 17 can open their own Junior ISA. They can also open an adult Cash ISA at 16, meaning they can technically hold both simultaneously for two years — though the Junior ISA remains locked until 18.
How to open a Junior ISA
The family gifting network — why it matters
Most grandparents want to do something meaningful for their grandchildren's future. Most end up giving cash at birthdays and Christmas that quickly disappears. The same amounts channelled into a Junior ISA compound tax-free for years.
Here's what that looks like in practice:
This is the core insight behind Amplifi — a Junior ISA platform built to make family contributions simple, so that grandparents, godparents, and family friends can all invest alongside parents with no friction.
Junior ISA vs Child Trust Fund — what's the difference?
Child Trust Funds (CTFs) were government-provided savings accounts for children born between 1 September 2002 and 2 January 2011. They've been replaced by Junior ISAs for new accounts, but many children in that age group still have CTFs.
The key differences: Junior ISAs generally offer more provider choice, better investment options, and lower fees than CTFs. You can transfer a CTF into a Junior ISA — and in most cases this is worth doing. You can't hold both simultaneously. If you're not sure whether your child has a CTF, you can check via the HMRC online service.
Choose your Junior ISA provider and start the transfer process with them — they'll handle the paperwork. The transfer doesn't count toward the £9,000 annual allowance. You'll need the CTF account details, which your current CTF provider can supply.