Texas Estates Code - EST § 356.302. Sale on Credit

(a) The cash payment for real estate of an estate sold partly on credit may not be less than one-fifth of the purchase price. The purchaser shall execute a note for the deferred payments, payable in monthly, quarterly, semiannual, or annual installments, in amounts that appear to the court to be in the estate's best interest. The note must bear interest from the date at a rate of not less than four percent per year, payable as provided in the note.

(b) A note executed by a purchaser under Subsection (a) must be secured by a vendor's lien retained in the deed and in the note on the property sold, and be further secured by a deed of trust on the property sold, with the usual provisions for foreclosure and sale on failure to make the payments provided in the deed and the note.

(c) At the election of the holder of a note executed by a purchaser under Subsection (a), default in the payment of principal, interest, or any part of the principal or interest, when due matures the entire debt.