On and after January 1, 2020, an ordinance or resolution imposing or discontinuing the tax hereunder or effecting a change in the rate thereof shall either: (i) be adopted and a certified copy thereof filed with the Department on or before the first day of April, whereupon the Department shall proceed to administer and enforce this Section as of the first day of July next following the adoption and filing; or (ii) be adopted and a certified copy thereof filed with the Department on or before the first day of October, whereupon the Department shall proceed to administer and enforce this Section as of the first day of January next following the adoption and filing.
55 ILCS 5/5-1035.1