Filing returns.

Every corporation, except a corporation all of whose income is exempt from taxation and except as provided in sub. (1m), shall furnish to the department a true and accurate statement, on or before the date on which the corporation is required to file for federal income tax purposes, not including any extension, under the Internal Revenue Code, in the manner and form and setting forth the facts the department deems necessary to enforce this chapter. Every corporation that is required to furnish a statement under this subsection and that has income that is not taxable under this subchapter shall include with the corporation’s statement a report that identifies each item of the corporation’s nontaxable income. The statement shall be subscribed by the president, vice president, treasurer, assistant treasurer, chief accounting officer, or any other officer duly authorized so to act. In the case of a return made for a corporation by a fiduciary, the fiduciary shall subscribe the return. The fact that an individual’s name is subscribed on the return shall be prima facie evidence that the individual is authorized to subscribe the return on behalf of the corporation.