(a) On or after the date the results are declared of an election held under § 3984.0602, at which the voters approved imposition of the tax authorized by this subchapter, the board shall determine and adopt by resolution or order the initial rate of the tax, which must be in one or more increments of one-eighth of one percent.
(b) After the election held under § 3984.0602, the board may increase or decrease the rate of the tax by one or more increments of one-eighth of one percent.
(c) The initial rate of the tax or any rate resulting from subsequent increases or decreases may not exceed the lesser of:
(1) the maximum rate authorized by the district voters at the election held under § 3984.0602; or
(2) a rate that, when added to the rates of all sales and use taxes imposed by other political subdivisions with territory in the district, would result in the maximum combined rate prescribed by § 321.101(f), Tax Code, at any location in the district.