(1)    Except as provided in sub. (2), the tax imposed by this chapter on individuals and the rates under s. 71.06 (1), (1m), (1n), (1p), (1q), and (2) shall apply to the Wisconsin taxable income of estates or trusts, except nuclear decommissioning trust or reserve funds, and that tax shall be paid by the fiduciary.

   (2)   Each electing small business trust, as defined in section 1361 (e) (1) of the Internal Revenue Code, is subject to tax at the highest rate under s. 71.06 (1), (1m), (1n), (1p), or (1q), whichever taxable year is applicable, on its income as computed under section 641 of the Internal Revenue Code, as modified by s. 71.05 (6) to (12), (19) and (20).