Tex. Gov't Code § 2003.901

As an alternative to filing an appeal under Section 42.01, Tax Code, a property owner may appeal to the office an appraisal review board order determining a protest concerning the appraised or market value of property brought under Section 41.41(a)(1) or (2), Tax Code, if the appraised or market value, as applicable, of the property that was the subject of the protest, as determined by the board order, is more than $1 million.