Tex. Elec. Code § 254.158

If the campaign treasurer appointment of a general-purpose committee filing monthly reports is filed after January 1 of the year in which monthly reports are filed, the period covered by the first monthly report begins the day the appointment is filed and continues through the 25th day of the month in which the appointment is filed unless the appointment is filed the 25th or a succeeding day of the month. In that case, the period continues through the 25th day of the month following the month in which the appointment is filed.