The Commission may, after hearing, require licensees and public utilities to carry a proper and adequate depreciation account in accordance with such rules, regulations, and forms of account as the Commission may prescribe. The Commission may, from time to time, ascertain and determine, and by order fix, the proper and adequate rates of depreciation of the several classes of property of each licensee and public utility. Each licensee and public utility shall conform its depreciation accounts to the rates so ascertained, determined, and fixed. The licensees and public utilities subject to the jurisdiction of the Commission shall not charge to operating expenses any depreciation charges on classes of property other than those prescribed by the Commission, or charge with respect to any class of property a percentage of depreciation other than that prescribed therefor by the Commission. No such licensee or public utility shall in any case include in any form under its operating or other expenses any depreciation or other charge or expenditure included elsewhere as a depreciation charge or otherwise under its operating or other expenses. Nothing in this section shall limit the power of a State commission to determine in the exercise of its jurisdiction, with respect to any public utility, the percentage rate of depreciation to be allowed, as to any class of property of such public utility, or the composite depreciation rate, for the purpose of determining rates or charges.

The Commission, before prescribing any rules or requirements as to accounts, records, or memoranda, or as to depreciation rates, shall notify each State commission having jurisdiction with respect to any public utility involved, and shall give reasonable opportunity to each such commission to present its views, and shall receive and consider such views and recommendations.

(June 10, 1920, ch. 285, pt. III, § 302, as added Aug. 26, 1935, ch. 687, title II, § 213, 49 Stat. 855.)