On or before April 1 of each year, every freight line company, equipment company, and mercantile company owning, operating, renting or leasing any freight car or cars which are moved over or used in the operation of the line of any railroad company wholly or partially within this state, shall prepare and file with the Oklahoma Tax Commission a true and accurate statement showing the gross earnings in this state on each freight car owned, operated, leased or rented by such company within the twelve-month period ending December 31 next preceding the date of the report; provided:
Such statements shall be subscribed and sworn to by the president, secretary or general accounting officer of the company, and shall be made on forms prescribed and furnished by the Tax Commission, and shall contain such other information as the Commission shall deem necessary to enable it to correctly compute the taxes due upon all such freight cars.
Okla. Stat. tit. 68, § 2205