He still haven't paid me yet and I hadn't that great of an experience with this person, he has a business with developers but seek freelancers for working at internal projects, it's messed up pretty bad, almost wanted to drop it after seeing the code.

Also, he's the business owner and he's the one that don't want to pay extra taxes...

I thought of charging more, but I'd rather just end it fast and forget all about that idiot.