Indiana Code Title 6. Taxation § 6-9-35-11

Sec. 11. The county fiscal body may adopt an ordinance requiring that any tax imposed under this chapter be reported on forms approved by the county treasurer and that the tax be paid monthly to the county treasurer.  If such an ordinance is adopted, the tax shall be paid to the county treasurer not more than twenty (20) days after the end of the month the tax is collected, and the county treasurer is responsible for collecting the tax and enforcing any of the provisions of IC 6-2.5 with respect to the tax.  If such an ordinance is not adopted, the tax shall be imposed, paid, and collected in the same manner that the state gross retail tax is imposed, paid, and collected under IC 6-2.5.  However, the return to be filed for the payment of the taxes may be made on separate returns or may be combined with the return filed for the payment of the state gross retail tax, as prescribed by the department of state revenue.