Title Transfer
You Have 30 Days to Put a Used Car in Your Name
When you buy a truck off a neighbor down in Mathis or Aransas Pass, the deal isn't really done until the title is in your name, and that happens at Marcela Thormaehlen's Tax Assessor-Collector office, the main one at 1301 E. Sinton St., Suite C. The county tax office is where titles transfer, registration renews, address changes get made, and temporary registration is issued.
Texas gives you 30 days from the date of sale to get the vehicle titled in your name. Let that slide and the late-transfer penalties start stacking up, so it's not a deadline to put off for a season.
Here's something that makes the whole thing easier: TxDMV suggests the seller come with you to the tax office to hand off the title and finish the signatures in one sitting. That heads off the kind of mess where a seller signs the wrong line or the odometer reading doesn't match. The county also runs branch offices in Aransas Pass, Mathis, and Portland, so you don't always have to drive into Sinton.
Source to confirm: TxDMV — San Patricio County Tax Office