Texas Transportation Code - TRANSP § 286.044. Assessment Liens on Certain Exempt Property

(a) The county may not assess a lien against property that on the date the commissioners court orders the assessment is exempt by law from execution on a judgment for debt.

(b) A property owner may waive an exemption to which the owner is entitled and voluntarily grant an assessment lien against the property in the same manner provided by law for granting a mechanic's lien for a homestead improvement.