Thanks for the info, so far I have been charging tax every time except when it is labor only, anything else on the invoice and the whole thing gets charged tax. What brought this up is a builder that I do work for gives his client a budget for everything involving the building process for the house, but has an agreement that any change orders he charges 10% on for his fee, so the builder has no problem with me showing the customer the estimates for what he wants to add. He added some central vac outlets, added items to the security system, added a surround system, 4 zones of audio and lighting control for 50% of the house, but then went off on the builder because I was charging tax for everything. I talked to the electrician that works for the builder and he only charges tax on materials never on labor and the builder thinks labor should never be taxed. I will go to that link and hopefully print something out to show the builder, thanks Ernie and everyone else for the replies.