1. (a) Notwithstanding the provisions of sections 12-223a to 12-223e, inclusive, the tax due in relation to any corporations which have filed a combined return for any income year with other corporations for the tax imposed under this chapter in accordance with section 12-223a shall be determined as follows:

   1. (1) The tax which would be due from each such corporation if it were filing separately under this chapter shall be determined, and the total for all corporations included in the combined return shall be added together; (2) the tax which would be jointly due from all corporations included in the combined return in accordance with the provisions of said sections 12-223a to 12-223e, inclusive, shall be determined; and (3) the total determined pursuant to subdivision (2) of this section shall be subtracted from the amount determined pursuant to subdivision (1) of this section. The resulting amount, in an amount not to exceed five hundred thousand dollars, shall be added to the amount determined to be due pursuant to said sections 12-223a to 12-223e, inclusive, and shall be due and payable as a part of the tax imposed pursuant to this chapter.
2. (b) The provisions of this section shall not apply to income years commencing on or after January 1, 2016.

(P.A. 89-251, S. 23, 203; June 30 Sp. Sess. P.A. 03-6, S. 80; June Sp. Sess. P.A. 09-3, S. 103; Sept. Sp. Sess. P.A. 09-8, S. 39; P.A. 15-244, S. 161; June Sp. Sess. P.A. 15-5, S. 139, 151.)

History: P.A. 89-251, Sec. 23 effective July 1, 1989, and applicable to income years commencing on or after January 1, 1990; June 30 Sp. Sess. P.A. 03-6 increased the potential supplementary tax determined under this section from $25,000 to $250,000, effective August 20, 2003, and applicable to income years commencing on or after January 1, 2003; June Sp. Sess. P.A. 09-3 increased maximum tax from $250,000 to $500,000, effective September 9, 2009; Sept. Sp. Sess. P.A. 09-8 changed effective date provisions of June Sp. Sess. P.A. 09-3, S. 103, from September 9, 2009, to September 9, 2009, and applicable to income years commencing on or after January 1, 2009, effective October 5, 2009; P.A. 15-244 designated existing provisions as Subsec. (a) and added Subsec. (b) re section not to apply to income years commencing on or after January 1, 2015, effective June 30, 2015, and applicable to income years commencing on or after January 1, 2015; June Sp. Sess. P.A. 15-5 changed effective date of P.A. 15-244, S. 161, from June 30, 2015, and applicable to income years commencing on or after January 1, 2015, to January 1, 2016, and applicable to income years commencing on or after that date, effective June 30, 2015, and amended Subsec. (b) to provide that section not apply to income years commencing on or after January 1, 2016, effective January 1, 2016, and applicable to income years commencing on or after that date.