That's very helpful.
My next question is:
Will I need to add his income (or at least mention it) on my working family tax credit forms?
Are they going to take his income into account and reduce my WFTC income?
If yes, do you have a rough idea how they approach it; for instance, if I have a WFTC income of £5000pa and a child tax credit income of £5000pa.
Great news - a lot of worry off my shoulders.
Would it be beneficial for me to set up a separate bank account in my name to make it easier to withdraw and refer his income?
If I do this, would it in any way be seen as my income (and taxable)?
I'm not sure with Paypal whether the age of the bank account holder will be a restriction when linked to the Paypal account.
Would it be a viable solution to keep the Paypal account of my brother's, but link the Paypal withdrawals to my son's bank account (if it can be done)?
Or would it be better in HMRC's eyes for me to open a new Paypal account in my name, but link my son's bank account if possible.