Indiana Code Title 8. Utilities and Transportation § 8-1-2-19

Sec. 19. (a) Every public utility shall carry a separate, proper and adequate depreciation account whenever the commission, after investigation, shall determine that such depreciation account reasonably can be required.

(b) The commission, from time to time, shall ascertain and determine the proper and adequate rates of depreciation of the several classes of property of each public utility.  Depreciation rates under this subsection shall be calculated to recover a reasonable estimate of the future cost of removing retired assets of the public utility.

(c) A public utility's rates, tolls and charges shall be such as will provide the amounts required over and above the reasonable and necessary operating expenses, to maintain such property in an operating state of efficiency corresponding to the progress of the industry.  In a proceeding in which the costs of a capital asset are being recognized for ratemaking purposes, a public utility may account for any asset retirement obligations and recover, through rates charged to customers, reasonably and prudently incurred costs associated with asset retirement obligations, to the extent the specific asset retirement obligation costs are incremental and have not otherwise been included in depreciation rates.  Each public utility shall conform its depreciation accounts to the rates so ascertained and determined by the commission.

(d) Subject to IC 8-1-8.5-2.1(d), the commission shall make changes in a public utility's rates of depreciation, from time to time, as the commission finds necessary, including as necessary to reflect changes in: