Indiana Code Title 8. Utilities and Transportation § 8-2.1-22-24

Sec. 24. (a) Every contract carrier by motor vehicle shall:

(b) A contract carrier may not, unless otherwise provided by this chapter, engage in the transportation of passengers or household goods in intrastate commerce unless the minimum charges for the transportation by the carrier have been published, filed, and posted in accordance with this chapter.  A reduction may not be made in the charge either directly or by means of any change in any rule or practice affecting the charge or the value of service under the charge, except after thirty (30) days notice of the proposed change filed in the required form and manner the department may, for good cause shown, allow a change upon less notice.  However, the notice must plainly state the change proposed to be made and the time when the change will take effect.

(c) A carrier shall not demand, charge, or collect less compensation for the transportation than the charges filed in accordance with this section, as affected by any rule or practice so filed, or as may be prescribed by the department.  It is unlawful for the carrier, by the furnishing of special service, facilities, or privileges, or by any other device, to charge, accept, or receive less than the minimum charges so filed or prescribed.