Ind. Code § 6-6-6.5-8
(2) not later than thirty-one (31) days after the purchase date;
unless the person presents proof to the department that the gross retail tax or use tax has already been paid with respect to the purchase of the aircraft or proof that the taxes are inapplicable because of an exemption.
Formerly: Acts 1975, P.L.68, SEC.1. As amended by Acts 1977, P.L.87, SEC.3; Acts 1980, P.L.74, SEC.24; P.L.100-1987, SEC.2; P.L.65-1997, SEC.8; P.L.97-1998, SEC.3.