I have an Estimate/Work authorization contract, serves 2 purposes well more than 2 legally!! 1- its the written estimate 2- if the HO chooses our service they sign where designated agreeing to the terms.
this is their invoice!! however I have seen in my area disclaimers on the competitions invoices, such as; once payment in full is received the contractor is not responsible for any damages visible or not!! this seems sneeky to me!!! just be honest & protect yourself!!!
theres alot of sample invoices out there, find one have your atty. look at it and go from there.
good luck
LXT..........