Returns and income derived from growth and/or dividends within a Junior GIA are taxable but you may be able to use the child’s annual tax allowances. If income generated from contributions from a parent exceeds £100 then this is treated as the parent’s income for tax purposes.
The rate of income tax payable on dividend income depends on the overall level of your income. Income tax may be payable whether you choose to receive dividend income or to reinvest it.
If a gain is made as a result of selling, or otherwise disposing of investments within your GIA and the amount of the gain exceeds your available capital gains tax allowance, capital gains tax will be payable.
It would be advisable for you to seek further tax guidance on this as we cannot provide tax advice.