Texas Code of Criminal Procedure - CRIM P Art. 42.08. Cumulative or concurrent sentence

(a) When the same defendant has been convicted in two or more cases, judgment and sentence shall be pronounced in each case in the same manner as if there had been but one conviction. Except as provided by Subsections (b) and (c), in the discretion of the court, the judgment in the second and subsequent convictions may either be that the sentence imposed or suspended shall begin when the judgment and the sentence imposed or suspended in the preceding conviction has ceased to operate, or that the sentence imposed or suspended shall run concurrently with the other case or cases, and sentence and execution shall be accordingly; provided, however, that the cumulative total of suspended sentences in felony cases shall not exceed 10 years, and the cumulative total of suspended sentences in misdemeanor cases shall not exceed the maximum period of confinement in jail applicable to the misdemeanor offenses, though in no event more than three years, including extensions of periods of community supervision under Article 42A.752(a)(2), if none of the offenses are offenses under Chapter 49, Penal Code, or four years, including extensions, if any of the offenses are offenses under Chapter 49, Penal Code.

(b) If a defendant is sentenced for an offense committed while the defendant was an inmate in the Texas Department of Criminal Justice and serving a sentence for an offense other than a state jail felony and the defendant has not completed the sentence he was serving at the time of the offense, the judge shall order the sentence for the subsequent offense to commence immediately on completion of the sentence for the original offense.

(c) If a defendant has been convicted in two or more cases and the court suspends the imposition of the sentence in one of the cases, the court may not order a sentence of confinement to commence on the completion of a suspended sentence for an offense.