Self-Assessment for 16 year old Son

My Son who is 16 has started a 3d printing business, however due to his age, the Etsy, Ebay and Amazon accounts are in my name. When I receive the payments, I send these directly to his account. How would this work with self-assessment? I also purchased his equiptment and ongoing materials again due to me having a Amazon and AliExpress accounts, how do we manage this when he is running it all? Thanks!

Hi,
As you are the parental guardian due to him being a minor you will declare the income and expenses as his.
You need to register him for self assessment with you as the guardian.
Thank you.