Ind. Code § 6-2.5-5-16
Transactions involving tangible personal property, accommodations, public utility commodities, and public utility service are exempt from the state gross retail tax, if the person acquiring the property, accommodations, commodities, or service:
(2) predominantly uses the property, accommodations, commodities, or service to perform its governmental functions.
As added by Acts 1980, P.L.52, SEC.1. Amended by P.L.25-1991, SEC.3; P.L.1-1996, SEC.45; P.L.293-2013(ts), SEC.4.