The officially prescribed carrier envelope for voting under this subchapter shall be prepared so that it can be mailed free of United States postage, as provided by the federal Uniformed and Overseas Citizens Absentee Voting Act (52 U.S.C. Sections 20301 through 20311), and must contain the label prescribed by Section 101.056(a) for the envelope in which the balloting materials are sent to a voter. The secretary of state shall provide early voting clerks with instructions on compliance with this section.