Tex. Transportation Code § 312.045: RIGHT TO APPEAL.

(a) A property owner against whose property or against whom the assessment has been made may bring suit to set aside or correct the assessment or any proceeding related to the assessment. The suit or proceeding must be brought not later than the 20th day after the date on which an assessment is made.

(b) After the period provided by Subsection (a), the property owner and the property owner's successors are barred from:

(1) any action to set aside or correct the assessment or a related proceeding; and

(2) raising a defense that alleges the invalidity of the assessment or of a related proceeding in any action in which the invalidity may be raised.

Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.