I understand what you mean about having less patience for him. It doesn't mean you shouldn't keep trying to treat him the same as the others, but I know from experience that it's hard sometimes when the parents are being idiots. Why not just implement a late fee for late payment, and have in your contract that after three late payments you terminate? I had to do this. Most of my families are awesome at paying me on time but there was always the ONE family that forgot EVERY Friday that it was payday. Luckily they left this summer and after they did I started this new late fee thing and it's working out great...the new family who started seems like they would totally have followed suit and paid late every week but because they paid the late fee once they seem to be getting their ducks in a row now.