Thank you for your question. Please permit me to assist you with your concerns.
You are indeed correct with your belief. Please look to Section 16.004 of the Texas Civil Practice & Remedies Code which I have provided to you below for review. Just please be aware that includes any action and any situation where you never 'assumed' the debt or promised to pay it back, as that can restart the statutory period.
Sec. 16.004. FOUR-YEAR LIMITATIONS PERIOD. (a) A person must bring suit on the following actions not later than four years after the day the cause of action accrues:
(1) specific performance of a contract for the conveyance of real property
(2) penalty or damages
on the penal clause of a bond to convey real property;
(4) fraud; or
(5) breach of fiduciary duty.
(b) A person must bring suit on the bond of an executor, administrator, or guardian not later than four years after the day of the death, resignation, removal, or discharge of the executor, administrator, or guardian.
(c) A person must bring suit against his partner for a settlement of partnership accounts, and must bring an action on an open or stated account, or on a mutual and current account concerning the trade of merchandise between merchants or their agents or factors, not later than four years after the day that the cause of action accrues. For purposes of this subsection, the cause of action accrues on the day that the dealings in which the parties were interested together cease.
Acts 1985, 69th Leg., ch. 959, Sec. 1, eff. Sept. 1, 1985. Amended by Acts 1999, 76th Leg., ch. 950, Sec. 1, eff. Aug. 30, 1999.
This section was amended by the 84th Legislature. Pending publication of the current statutes, see H.B. 189, 84th Legislature, Regular Session, for amendments affecting this section.