What documents do I need to renew car tax for a vehicle over 6 years old in Thailand?

To renew the tax for a car over 6 years old in Thailand, you primarily need the blue book (vehicle registration document) and may also want to bring the Por Ro Bor. The need for additional documents like a work permit or passport is generally unnecessary, as many users report that ID was never requested during their tax renewal process. It's advisable to take the car to a local testing station where they can handle everything, including tax and insurance. Ensure your vehicle has undergone the necessary inspections, especially if it is over 7 years old, as an inspection letter may be required.