Indiana Code Title 6. Taxation § 6-9-29.5-4

Sec. 4. (a) If an ordinance is adopted under this article, the adopting body must immediately send a certified copy of the ordinance to the commissioner of the department of state revenue.  Notwithstanding any other provision in this article, if the department of state revenue collects the revenue from the food and beverage tax, the department of state revenue shall begin collecting the tax as provided in the ordinance for periods beginning on or after the later of:

(b) If an ordinance does not specify an effective date, the ordinance shall be considered effective on the earliest date allowable under this section.