Miss. Code Ann. § 27-35-303: Miss. Code Ann. § 27-35-303

(1) Each person, firm, company or corporation owning and/or operating a railroad, oil or gas pipeline company, electric company or any other company listed in Section 27-35-301 , owning property not situated wholly in one (1) county; and any telephone company owning property in more than six (6) counties shall, on or before the first day of April in each year, file with the Department of Revenue a complete schedule, under oath, on forms prescribed and furnished by the Department of Revenue, of all its property, real or personal, taxable and nontaxable, owned by it on the first day of the preceding January, setting forth therein the value of the whole, the total amount of capital stock, its par value and its actual value, and the value of its franchise, the gross amount of receipts in the year preceding; all real, personal or mixed property belonging to the company within the state, not enumerated, with its value; a list of all lands in this state owned, describing the same and giving the value thereof, the gross amount of receipts the year preceding earned within and from this state; and if any of said property is claimed to be exempt from taxation, it shall be separately stated and valued, and the law cited under which the claim is made. It shall not be necessary that a rendition on any motor vehicles be made as defined by the “Motor Vehicle Ad Valorem Tax Law of 1958.” In addition to these required schedules, the Department of Revenue may require each person, firm, company or corporation to file with the Department of Revenue a copy of any annual report or form required to be filed by him with any federal regulatory agency. The Department of Revenue may grant an extension of up to twenty (20) days for the filing of the schedules required by this section.

(2) The Department of Revenue shall have the power to adopt, amend or repeal such rules and regulations as necessary to implement tax duties assigned to it in this section.