Thanks Kirby. This is very weird to me , as i know that i should charge the sale tax to this client. However, i asked one of construction contractor who's been working in this remodeling house industry for years. He said that it's up to me if i want to charge or not. There is no doubt that i should charge it according to the Comptroller Account Office. But , i just wonder how that guy not charge sale tax in such cases. And he's not yet got audited yet!