Texas Constitution art. 8 §18

(a) The Legislature shall provide for equalizing, as near as may be, the valuation of all property subject to or rendered for taxation, and may also provide for the classification of all lands with reference to their value in the several counties. (b) A single appraisal within each county of all property subject to ad valorem taxation by the county and all other taxing units located therein shall be provided by general law. The Legislature, by general law, may authorize appraisals outside a county when political subdivisions are situated in more than one county or when two or more counties elect to consolidate appraisal services. (c) The Legislature, by general law, shall provide for a single board of equalization for each appraisal entity consisting of qualified persons residing within the territory appraised by that entity. The Legislature, by general law, may authorize a single board of equalization for two or more adjoining appraisal entities that elect to provide for consolidated equalizations. Members of a board of equalization may not be elected officials of a county or of the governing body of a taxing unit. (d) The Legislature shall prescribe by general law the methods, timing, and administrative process for implementing the requirements of this section. (Feb. 15, 1876. Amended Nov. 4, 1980; Subsec. (c) amended Nov. 3, 2009.)