Tex. Const. art. 8, § 17

SPECIFICATION OF SUBJECTS NOT LIMITATION OF LEGISLATURE'S POWER OF TAXATION. The specification of the objects and subjects of taxation shall not deprive the Legislature of the power to require other subjects or objects to be taxed in such manner as may be,† consistent with the principles of taxation fixed in this Constitution. (Feb. 15, 1876.) † The language of this provision is identical to the language of the official legislative measure that originally proposed the provision. A digital image of the original text of the official enrolled measure can be found here .