Tex. Tax Code § 32.02 — RESTRICTIONS ON A MINERAL INTEREST TAX LIEN

(a) If a mineral estate is severed from a surface estate and if different persons own the mineral estate and surface estate, the lien resulting from taxes imposed against each interest in the mineral estate exists only for the duration of the interest it encumbers. After an interest in the mineral estate terminates, the lien encumbering it expires and is not enforceable: (1) against any part of the surface estate not owned by the owner of the interest encumbered by the lien; (2) against any part of the mineral estate not owned by the owner of the interest encumbered by the lien; or (3) against the owner of the surface estate as a personal obligation, unless he also owns the interest encumbered by the lien. (b) Taxes imposed on a severed interest in a mineral estate that has terminated remain the personal liability of the person who owned the interest on January 1 of the year for which the tax was imposed. Acts 1979, 66th Leg., p. 2287, ch. 841, Sec. 1, eff. Jan. 1, 1982.