(a) The investments of foreign and alien insurers shall be as permitted by the laws of their domicile but shall be of a quality substantially as high as those required under this article for similar funds of like domestic insurers.

(b) For the purposes of this Code section the domicile of an alien insurer, other than insurers formed under the laws of Canada, shall be that state designated by the insurer in writing filed with the Commissioner at time of admission to this state and may be any one of the following states:

(1) This state if the insurer is entering through this state to transact insurance in the United States through a United States branch;

(2) That in which the insurer was first authorized to transact insurance;

(3) That in which is located the insurer's principal place of business in the United States; or

(4) That in which is held the larger deposits of trusteed assets of the insurer for the protection of its policyholders and creditors in the United States.

(c) If the insurer makes no such designation, its domicile shall be deemed to be that state in which is located its principal place of business in the United States.

(d) In the case of the insurer formed under the laws of Canada or a province of Canada, its domicile shall be deemed to be that province in which its head office is situated.