Interest earned from money given by grandmother

My son (aged 14) received certain amount of money from his grandmother. He put the money in the bank account. What happen if the interest earned in a tax year (let's say 2023/24) reached more than GBP 5,000. Does my son need to file a Self Assesment, and does he need to pay tax on it?

Hi Frankie Chow,
A Self Assessment return would only be required to declare savings income of £10,000 or over.
While the £5000 is classed as taxable income, your son (depending on his other income) may be entitled to the tax-free starting rate for savings of £5000, and the Personal Savings allowance of £1000, in addition to his tax free allowance of £12570.
You can find more information here:
Tax on savings interest
Thank you.