If you're an independent insurance adjustor, an inspector, an actuarial analyst, an appraiser, an investigator, a claims processor, or a loss prevention consultant, you should be collecting sales and use taxes.
You should collect state tax, plus any local (city, county, special purpose district, or transit) taxes, from your customer on the total amount you bill for your insurance service.
Here are some general descriptions to use as guidelines:
Even if your customer is not based in Texas, tax is due on your insurance service if your customer is doing business in Texas and if the person or property you are inspecting, appraising, investigating, etc., also is in Texas.
You should pay tax on all materials, supplies, and equipment used to perform the service.
At times, you may subcontract with a third party to do an insurance service for you. These folks will bill you. You, in turn, will bill your customer. You may give the third party a resale certificate in lieu of tax on the service. You will then collect tax from your customer on your total charge.
Please see Rule 3.355 - Insurance Services.