Indiana Code Title 6. Taxation § 6-3.5-10-4

Sec. 4. (a) After January 1 but before September 1 of any year, the fiscal body of an adopting municipality may, subject to the limitations imposed by subsection (b), adopt an ordinance to rescind the surtax.  If a fiscal body adopts an ordinance to rescind the surtax, the surtax does not apply to a vehicle registered after December 31 of the year in which the ordinance is adopted.

(b) A fiscal body may not adopt an ordinance to rescind the surtax unless the fiscal body concurrently adopts an ordinance under IC 6-3.5-11 to rescind the municipal wheel tax.