Timely-amended federal income tax returns

(a) General. If the amount of a taxpayer's federal income is changed or corrected by the Internal Revenue Service or other competent authority, or as the result of a renegotiation of a contract or subcontract with the United States, or the amount an employer is required to deduct and withhold from wages for federal income tax withholding purposes is changed or corrected by such service or authority, or if a taxpayer's claim for credit or refund of federal income tax is disallowed in whole or in part, the taxpayer or employer shall report such change or correction in federal income or federal income tax withholding or such disallowance of the claim for credit or refund of federal income tax to the Department by filing, on or before the date that is 90 days after the final determination of such change, correction, renegotiation or disallowance, an amended return, as described in subsection (b) of this section, and shall concede the accuracy thereof or state wherein it is erroneous, but only if the federal change or correction, results of renegotiation or disallowance increases or decreases a taxpayer or employer's Connecticut income tax liability. Such report may be required at any other time if the Commissioner deems it necessary. For purposes of this section, the term "federal income" means federal adjusted gross income or federal alternative minimum taxable income of an individual, and federal taxable income of a trust or estate prior to deductions relating to distributions to beneficiaries or federal alternative minimum taxable income of a trust or estate and "taxpayer's Connecticut income tax liability" means the liability for Connecticut income tax, as defined in § 12-701(b)-1(a)(10) of this part. (b) Form of report. (1) With respect to a change or correction in a taxpayer's federal income or federal alternative minimum taxable income or the disallowance in whole or in part of a claim for credit or refund of federal income tax, the taxpayer shall make the report that is referred to in subsection (a) of this section on a Form CT-1040X, or Form CT-1041, CT-1065, CT-G, or CT-1120SI, as the case may be, with the appropriate box checked to indicate that an amended return is being filed. This form shall be accompanied by a copy of the final federal determination or renegotiation agreement as well as any of the pertinent data in all cases in which a Connecticut income tax refund, based on such final determination or renegotiation, is claimed. Where additional Connecticut income tax is due, the form shall be accompanied by full payment of any additional Connecticut income tax shown to be due thereon and shall be forwarded separately from, and not as part of, any other report or Connecticut income tax return, and the taxpayer may, in lieu of a copy of the final determination or renegotiation agreement, give full details of the changes on the prescribed form. (2) With respect to a change or correction in the amount that an employer is required to deduct and withhold from wages for federal income tax withholding purposes, the employer shall make the report that is referred to in subsection (a) of this section on Form CT-941X. In lieu of the Form CT-941X, the employer may submit either a copy of the final federal determination or renegotiation agreement or a detailed explanation of the final federal determination or renegotiation agreement, together with a statement showing the inclusive dates of the period involved, the amount of Connecticut income tax that was originally withheld and reported and the amount of Connecticut income tax that should have been withheld and reported. Any Connecticut income tax which an employer is required to deduct and withhold as a result of a federal change or correction shall accompany the report. (3) A husband and wife who file a joint federal income tax return but who are required to file separate Connecticut income tax returns shall file separate forms to report federal adjustments affecting their Connecticut income tax returns. Each report shall show the changes made on the federal income tax return attributable to the reporting spouse. These separate reports shall be filed together. If the federal changes are attributable solely to one spouse, that spouse shall file a Form CT-1040X to report the federal changes. However, such form shall include the name and social security number of the nonreporting spouse and contain a statement that the federal changes do not affect the separate Connecticut income tax return of the nonreporting spouse. (c) The provisions of this section also apply to any individual whose computation of tax under section 1341(a)(4) or (5) of the internal revenue code is changed or corrected by the Internal Revenue Service or other competent authority, but only if the change or correction increases or decreases the individual's Connecticut income tax liability.