Conn. Gen. Stat. § 12-221a

(b) With respect to any company subject to the tax imposed under this chapter, the commissioner, at any time within three years after the due date for the filing of such return, or in the case of a completed return filed after such due date, within three years after the date on which such return was received by the commissioner, which return is based on the method of apportionment provided for in said sections 12-218 , 12-218a and 12-219a , may change such method if, in his opinion, such method has operated or will operate so as to subject the company to taxation on a lesser portion of its net income or minimum tax base than is equitably attributable to this state and shall thereupon proceed to assess and collect taxes in accordance with such method as so changed by him. On and after January 1, 1995, the commissioner may change such method only in accordance with regulations establishing standards for such action, which the commissioner may adopt in accordance with the provisions of chapter 54.

(c) The provisions of this section shall also apply to a combined group required to file a combined unitary tax return pursuant to section 12-222 .

Cited. 202 C. 412; 236 C. 156.

Under former section, taxpayer could not, on its own initiative, omit filing the return prescribed by statute and file only a return pursuant to an alternative method which had not yet been accepted or approved by tax commissioner. 26 CS 373. Cited. 41 CS 271; 44 CS 90.