Tesla FedExs you the docs, the inspection paper will be in the glove box. You take both to the County Tax Office and pay your sales tax. Tesla tried to handle the paperwork last year, but Texas only assigned one person to handle the paperwork so people waited weeks before their car was delivered. Tesla went back to the older system which got the cars in the hands of the purchasers much sooner. This is not Tesla's fault, it's the fault of the dealer association which has basically purchased the Legislators and tasked them with doing everything possible to prevent Tesla and their customers from having a good experience. So far it's not working (fortunately).