(a)(1) Notwithstanding any provision of the general statutes, and except as otherwise provided in subdivision (5) of this subsection or in subsection (b) of this section, the amount of tax credit or credits otherwise allowable against the tax imposed under this chapter for any calendar year shall not exceed seventy per cent of the amount of tax due from such taxpayer under this chapter with respect to such calendar year of the taxpayer prior to the application of such credit or credits.

(2) For the calendar year commencing January 1, 2011, “type one tax credits” means tax credits allowable under § 12-217jj, 12-217kk or 12-217ll; “type two tax credits” means tax credits allowable under § 38a-88a; “type three tax credits” means tax credits that are not type one tax credits or type two tax credits; “thirty per cent threshold” means thirty per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credit; “fifty-five per cent threshold” means fifty-five per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits; and “seventy per cent threshold” means seventy per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits.

(3) For the calendar year commencing January 1, 2012, “type one tax credits” means the tax credit allowable under § 12-217ll; “type two tax credits” means tax credits allowable under § 38a-88a; “type three tax credits” means tax credits that are not type one tax credits or type two tax credits; “thirty per cent threshold” means thirty per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credit; “fifty-five per cent threshold” means fifty-five per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits; and “seventy per cent threshold” means seventy per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits.

(4) For calendar years commencing on or after January 1, 2013, “type one tax credits” means the tax credit allowable under sections 12-217jj, 12-217kk and 12-217ll; “type two tax credits” means tax credits allowable under § 38a-88a; “type three tax credits” means tax credits that are not type one tax credits or type two tax credits; “thirty per cent threshold” means thirty per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credit; “fifty-five per cent threshold” means fifty-five per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits; and “seventy per cent threshold” means seventy per cent of the amount of tax due from a taxpayer under this chapter prior to the application of tax credits.

(5) For calendar years commencing on or after January 1, 2011, and subject to the provisions of subdivisions (2), (3) and (4) of this subsection, the amount of tax credit or credits otherwise allowable against the tax imposed under this chapter shall not exceed:

(A) If the tax credit or credits being claimed by a taxpayer are type three tax credits only, thirty per cent of the amount of tax due from such taxpayer under this chapter with respect to said calendar years of the taxpayer prior to the application of such credit or credits.

(B) If the tax credit or credits being claimed by a taxpayer are type one tax credits and type three tax credits, but not type two tax credits, fifty-five per cent of the amount of tax due from such taxpayer under this chapter with respect to said calendar years of the taxpayer prior to the application of such credit or credits, provided (i) type three tax credits shall be claimed before type one tax credits are claimed, (ii) the type three tax credits being claimed may not exceed the thirty per cent threshold, and (iii) the sum of the type one tax credits and the type three tax credits being claimed may not exceed the fifty-five per cent threshold.

(C) If the tax credit or credits being claimed by a taxpayer are type two tax credits and type three tax credits, but not type one tax credits, seventy per cent of the amount of tax due from such taxpayer under this chapter with respect to said calendar years of the taxpayer prior to the application of such credit or credits, provided (i) type three tax credits shall be claimed before type two tax credits are claimed, (ii) the type three tax credits being claimed may not exceed the thirty per cent threshold, and (iii) the sum of the type two tax credits and the type three tax credits being claimed may not exceed the seventy per cent threshold.

(D) If the tax credit or credits being claimed by a taxpayer are type one tax credits, type two tax credits and type three tax credits, seventy per cent of the amount of tax due from such taxpayer under this chapter with respect to said calendar years of the taxpayer prior to the application of such credits, provided (i) type three tax credits shall be claimed before type one tax credits or type two tax credits are claimed, and the type one tax credits shall be claimed before the type two tax credits are claimed, (ii) the type three tax credits being claimed may not exceed the thirty per cent threshold, (iii) the sum of the type one tax credits and the type three tax credits being claimed may not exceed the fifty-five per cent threshold, and (iv) the sum of the type one tax credits, the type two tax credits and the type three tax credits being claimed may not exceed the seventy per cent threshold.

(E) If the tax credit or credits being claimed by a taxpayer are type one tax credits and type two tax credits only, but not type three tax credits, seventy per cent of the amount of tax due from such taxpayer under this chapter with respect to said calendar years of the taxpayer prior to the application of such credits, provided (i) the type one tax credits shall be claimed before type two tax credits are claimed, (ii) the type one tax credits being claimed may not exceed the fifty-five per cent threshold, and (iii) the sum of the type one tax credits and the type two tax credits being claimed may not exceed the seventy per cent threshold.

(b) The amount of the rebate computed under § 32-7t shall be treated as an offset of the tax due under this chapter and may exceed the amount specified in subsection (a) of this section. If the amount of the rebate allowed pursuant to § 32-7t exceeds the taxpayer’s liability for the tax imposed under this chapter, the commissioner shall treat such excess as an overpayment and shall refund the amount of such excess, without interest, to the taxpayer.