For tax years beginning after December 31, 1998, a qualified subchapter S subsidiary whose stock is 100% owned by an Alabama S corporation is disregarded and treated as a division of the parent. The parent S corporation will file a 20-S return with this state. An Alabama S corporation is any corporation with a valid election under 26 U.S.C. sections 1362 or 1362(b)(3) which conducts business within this state.