Hi @pcbruin1! If this is something your child is doing regularly and with an intent to turn a profit, and if it's his only income for the year, the filing requirement is if his net self-employment earnings (income after taking expenses into account) are more than $400. If he made over $600 selling on a single platform, he may receive a 1099-K reporting the income, and in that case I'd recommend filing a return even if the net earnings are less than $400. You may also want to check your state filing requirements.