A.  All items of gross income, not otherwise exempt, shall be segregated into two general classes designated as allocable income and apportionable income.

B.  Allocable income.  The class of gross income to be designated as “allocable income” shall include only the following:

(1)  Rents and royalties from immovable or corporeal movable property.

(2)  Royalties or similar revenue from the use of patents, trademarks, copyrights, secret processes, and other similar intangible rights.

(3)  Income from estates, trusts, and partnerships.

(4)  Income from construction, repair, or other similar services.

C.  Apportionable income.  The class of income to be designated as “apportionable income” shall include all items of gross income which are not properly includable in allocable income as defined in this Section.

Acts 1986, 1st Ex. Sess., No. 16, §1, eff. Dec. 24, 1986; Acts 1992, No. 1029, §1, eff. for taxable periods beginning on or after Jan. 1, 1992; Acts 1993, No. 690, §1, eff. June 21, 1993, for all taxable periods beginning after Dec. 31, 1992; Acts 2002, No. 16, §1, eff. June 7, 2002; Acts 2005, No. 401, §1, eff. for all taxable periods beginning after Dec. 31, 2005.