Oregon Revised Statutes Insurance § 731.096

(1) The domicile of an alien insurer, other than insurers formed under the laws of Canada or a province thereof, shall be that state designated by the insurer in writing filed with the Director of the Department of Consumer and Business Services at time of admission to this state or before January 1, 1962, whichever date is the later, and may be any one of the following states:

(2) 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.