Texas Estates Code - EST § 111.001. Right of Survivorship Agreements Authorized

(a) Notwithstanding Section 101.002, two or more persons who hold an interest in property jointly may agree in writing that the interest of a joint owner who dies survives to the surviving joint owner or owners.

(b) An agreement described by Subsection (a) may not be inferred from the mere fact that property is held in joint ownership.