The maximum amount you can pay into your child’s Junior ISA in the current tax year is £9,000 - this allowance is per child and can be split across a Cash JISA and a Stocks & Shares JISA. Contributions into JISAs don’t count towards your own ISA allowance of £20,000 per tax year.
The minimum amount you can pay into a Moneybox Junior ISA is £1. If you are making an easy bank transfer or receiving a Junior ISA Gift, the minimum payment is £100.
Please note that any contributions into a Junior ISA can only be withdrawn by the child once they turn 18, and so cannot be repaid.