I'm having trouble determining what is required to provide a customer in writing. I read the law and it looks like an estimate only has to be provide if requested, but not sure about the work order. The invoice for sure does.
I imaging you provide the work order before performing work, sort of a permission slip to do so, then an invoice at the end.
I think I figured it out. Estimates need to be provided if the customer requests it, Work orders need to be provided to customer if you keep written copies for yourself, attached to the invoice, with is required to be provided with a very specific breakdown of what was done to a specific vehicle.
I was asking a friend who is a service advisor at a large dealer what the provide and he was surprised to hear that they were supposed to provide a copy of the work order to the customer since they don't do it at his place.