Tex. Bus. Orgs. Code § 21.107
The existence of or a performance under a shareholders' agreement authorized by this subchapter is not a ground for imposing personal liability on a shareholder for an act or obligation of the corporation by disregarding the separate existence of the corporation or otherwise, even if the agreement or a performance under the agreement:
Acts 2003, 78th Leg., ch. 182, Sec. 1, eff. Jan. 1, 2006.