Conn. Gen. Stat. § 12-211

(b) Any tax obligation imposed by any city, county or other political subdivision of a state or foreign country on Connecticut insurance companies shall be deemed to be imposed by such state or foreign country within the meaning of this section. For the purposes of this section, the domicile of a foreign insurer shall be that state designated by the insurer in writing filed with said commissioner at the time of admission to this state or within six months after July 1, 1973, whichever date is later, and may be any one of the following states: (1) That in which the insurer was first authorized to engage in the insurance business; (2) that in which the principal place of business of such insurer in the United States is located; (3) that in which the largest deposit of trusteed assets of the insurer for the protection of its policyholders and creditors in the United States is held. Any designation so made hereunder shall be irrevocable and, if the insurer makes no such designation at or within the time provided herein, its domicile shall irrevocably be deemed to be that state in which the insurer was first authorized to engage in the insurance business in the United States. The domicile of an insurer formed under the laws of Canada or a province thereof shall be deemed to be that province in which its head office is situated.

(c) The provisions of this section shall not apply to ad valorem taxes on real or personal property, personal income taxes, fees for agents' licenses, special purpose assessments imposed in connection with particular kinds of insurance including, but not limited to, workers' compensation assessments and Insurance Guaranty Association Fund assessments, or to premium taxes on special health care plans as defined in section 38a-564 of the general statutes, revision of 1958, revised to January 1, 2013, and section 38a-551 , except in the case where another state or foreign country imposes upon Connecticut domiciled insurers retaliatory charges for such taxes, fees or assessments.

Annotations to former statute:

Recovery of tax paid under rule adopted in another state and later reversed. 79 C. 154. Rhode Island company doing business here is not entitled to deduct from gross premium income subject to tax, reinsurance premiums paid to a Connecticut company, which is not required to pay a tax to state on such premiums. 112 C. 472.

Annotation to present section:

1987 amendment clarified original intent; retaliatory tax not applicable for special purpose assessments discussed. 233 C. 243.