Texas Tax Code - TAX § 160.043. Payment by Seller

If the comptroller on an audit of the records of a seller finds that the amount of tax due was incorrectly reported on a joint affidavit and that the amount of tax paid was less than the amount due or that the seller failed to execute and deliver to the purchaser a joint affidavit and any other documents necessary to register the taxable boat or motor, the seller and purchaser are jointly and severally liable for the amount of the tax determined to be due.