Conn. Agencies Regs. § 12-708-4
Where a short taxable year for federal income tax purposes results from a change in accounting period, a person shall, where any of the conditions provided for in § 12-740-6 of Part XI are met, also file a Connecticut income tax return for such short taxable year. Such person's Connecticut taxable income shall be computed on the basis of the period for which the Connecticut income tax return is made and in accordance with the rules applicable to the determination of Connecticut taxable income generally, except that the amount of the personal exemption provided for in Section 12-702 of the general statutes that shall be allowed is that amount which bears the same ratio to the Connecticut exemption allowed as the number of months in the short taxable year bears to 12 months.
Conn. Agencies Regs. § 12-708-4