N.B.
If he's getting child support let him know that money is for his part of his bills, like to pay for the electricity he uses for his phone and computers and stuff if he has those things. That's it's to buy extras like food and milk and paper towels and toilet paper so he'll have those things to use.
But it's also supposed to be for some things he just wants. Not all the money has to go for needs.
Let him know that money is put there to cover those needs and if he wants more he needs to talk to mom. That's what I would say.