Tex. Transp. Code § 286.009
(a) Not later than the 15th day after the date the commissioners court makes an assessment under Section 286.002, a person who owns or claims an interest in the assessed property may appeal the assessment in district court. The person may contest:
(b) A person who does not bring a suit within the time provided by Subsection (a):
Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.