Conn. Gen. Stat. § 12-727
Informational returns from persons making payments. Notice of changes in federal tax return. Filing amended returns.
(b) (1) If the amount of a taxpayer's federal adjusted gross income, in the case of an individual, or federal taxable income, in the case of a trust or estate, reported on such taxpayer's federal income tax return for any taxable year is changed or corrected by the United States Internal Revenue Service or other competent authority, or as the result of a renegotiation of a contract or subcontract with the United States, the taxpayer shall provide notice of such change or correction in federal adjusted gross income or federal taxable income, as the case may be, to the commissioner by filing, on or before the date that is ninety days after the final determination of such change, correction or renegotiation, or as otherwise required by the commissioner, an amended return under this chapter and shall concede the accuracy of such determination or state wherein it is erroneous. The provisions of the preceding sentence shall also apply if an individual's computation of tax under Section 1341(a)(4) or (5) of the Internal Revenue Code is changed or corrected by the United States Internal Revenue Service or other competent authority. The commissioner may redetermine and the taxpayer shall be required to pay the tax for any taxable year affected, regardless of any otherwise applicable statute of limitations.
(2) Any taxpayer filing an amended federal income tax return with the United States Internal Revenue Service or other competent authority shall also file, on or before the date that is ninety days after the final determination is made on such amended return by the Internal Revenue Service or other competent authority, an amended return under this chapter and shall give such information as the commissioner may require. The commissioner shall treat any such amended return under this chapter reporting a tax overpayment as containing sufficient required information after proof of such final determination on such amended federal income tax return by the Internal Revenue Service or other competent authority is submitted to the commissioner. The commissioner may redetermine, and the taxpayer shall be required to pay the tax for any taxable year affected, regardless of any otherwise applicable statute of limitations.
(3) The commissioner may by regulation prescribe such exceptions to the requirements of this subsection as he deems appropriate.