I don't think you should charge him for that hour. You might instead try to charge him interest for being late (or add interest to payment plan). However, per

I don't think you should charge him for that hour. You might instead try to charge him interest for being late (or add interest to payment plan). However, personally, I think it's better to move on and instead spend your time diversifying your customer base. A friend of mine says the nice thing about consulting is "you can fire your customer."