Junior ISA calculator
See what a Junior ISA could be worth by your child's 18th birthday, saving in cash at an interest rate or invested at three illustrative growth rates. Payments from parents, family and friends are capped at the £9,000 yearly limit.
The Junior ISA runs until their 18th birthday.
From parents, family or friends, up to £9,000 a year in total, including any lump sum.
Starts at the top Junior Cash ISA rate in our table, 4.15% AER, checked 30 October 2026. Rates change over time.
Taken off each illustrative growth rate. Check what your provider charges.
What the Junior ISA could be worth at 18
Pot at 18
£31,899
Paid in
£21,600
Interest earned
£10,299
At 4.15% AER every year until 18. Rates change, so treat this as a guide.
At 2% a year
£25,018
At 5% a year
£33,331
At 8% a year
£44,989
Paid in
£21,600
Growth of 2%, 5%, 8% a year before 0.40% yearly charges. These are illustrations, not forecasts. Capital at risk: investments can fall as well as rise, and you may get back less than you put in.
Pot by age, at 4.15% AER
How this works
- A Junior ISA takes up to £9,000 a year in 2026/27, from anyone, separate from the adult £20,000 allowance. We cap each year's payments at that limit, counting any lump sum first, and assume the limit stays the same until the child turns 18.
- Monthly payments go in at the start of each month. In cash, the pot grows at the interest rate you enter, as an AER, every year until 18.
- Invested, the pot grows at three illustrative rates, 2%, 5% and 8% a year, minus the yearly charges you enter. These are illustrations, not forecasts: investments can fall as well as rise, and you may get back less than you put in.
- Interest and investment growth inside a Junior ISA are tax-free.
- Figures are rounded to the nearest pound.
What happens at 18
The child can manage the account from 16, choosing the provider and how it is invested, but cannot withdraw any money until 18. On their 18th birthday the Junior ISA becomes an adult ISA automatically, and they get full control of the money.
Compare Junior Cash ISA rates and Junior Stocks and Shares ISA platforms on our Junior ISA page, or see how a Junior ISA compares with Premium Bonds for a child.
Tax treatment depends on your circumstances and may change. This is not financial advice.
Questions people ask
How much can you put in a Junior ISA?
Up to £9,000 in the 2026/27 tax year, in total across a cash Junior ISA and a Stocks and Shares Junior ISA. The limit is separate from the adult £20,000 ISA allowance, so it does not use up any of a parent's own allowance.
Who can pay into a Junior ISA?
Anyone, once the account is open: parents, grandparents, other family and friends, as long as the total paid in across everyone stays within the £9,000 yearly limit.
When can the child take the money out?
Not until they turn 18. The child can manage the account from 16, but cannot withdraw any money until 18, when the account becomes an adult ISA and they get full control of it.
Can a child have a cash and a Stocks and Shares Junior ISA?
Yes, one of each, as long as total payments across both stay within the £9,000 yearly limit. Cash grows at an interest rate and does not fall in value with the markets; investments can rise or fall, and you may get back less than you put in.
Does the Cash ISA limit affect Junior ISAs?
No. The Cash ISA limit is for adult Cash ISAs and stays £20,000, after the planned cut to £12,000 was cancelled in the Budget on 28 October 2026. The Junior ISA limit stays £9,000 a year and sits outside the adult allowance. See the Cash ISA limit.