(1)    Every partnership shall furnish to the department a true and accurate statement, on or before the date on which the partnership 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. A partnership that is the owner of a single-owner entity that is disregarded as a separate entity under section 7701 of the Internal Revenue Code shall include that entity’s information on the owner’s return under this subchapter. The statement shall be subscribed by one of the partners of the partnership.

   (1m)   Every partnership that is required to file a return under sub. (1) shall, on or before the due date of the return, including extensions, provide a schedule to each partner whose share of income, deductions, credits, or other items of the partnership may affect the partner’s tax liability under this chapter. The schedule shall separately indicate the partner’s share of each item.

   (2)   Nothing in this section precludes the department of revenue from requiring any person other than a corporation to file an income tax return when in the judgment of the department a return should be filed.

   (3)   Any extension granted by law or by the Internal Revenue Service for the filing of the federal return that corresponds to the return required under sub. (1) extends the time for filing under this section.