Indiana Code Title 8. Utilities and Transportation § 8-1-13-29

Sec. 29. (a) Every corporation shall file with the commission, within a time fixed by the commission, schedules showing all rates, tolls, and charges that it has established and that are enforced at the time for any service performed by it within the state, or for any service in connection with the rates, tolls, and charges.

(b) The schedules of rates, tolls, and charges shall be open for public inspection.

(c) Every corporation shall file, with and as a part of the schedule, all rules that in any manner affect the rates charged or to be charged for any service.

(d) It is unlawful for a corporation to charge any amount for any service that varies from the schedules approved by the commission.