Ind. Code § 6-3-1-20 : TAXATION — STATE INCOME TAXES — DEFINITIONS —3-1-20 - "Business income" TEXT PDF The term "business income" means all income that is apportionable to the state under the Constitution of the United States. IC 6-3-1-20 Amended by P.L. 250-2015, SEC. 13, eff. 1/1/2016. Formerly: Acts 1963(ss), c.32, s.120; Acts 1965, c.233, s.7.