Texas Government Code - GOV'T § 312.016. Standard Time

(a) The standard time in this state is the time at the 90th meridian longitude west from Greenwich, commonly known as “central standard time.”

(b) The standard time in a region of this state that used mountain standard time before June 12, 1947, is the time at the 105th meridian longitude west from Greenwich, commonly known as “mountain standard time.”

(c) Unless otherwise expressly provided, a reference in a statute, order, or rule to the time in which an act shall be performed means the appropriate standard time as provided by this section.

(d) This state, acting as authorized under federal law, shall observe daylight saving time year-round.  This subsection applies to both the portion of this state using central standard time as the official standard time and the portion of this state using mountain standard time as the official standard time.  The standard time in this state shall be referred to as Texas Time.