Oregon Revised Statutes Revenue and Taxation § 308.810

(1) Every association referred to in ORS 308.805 shall make and file with the Department of Revenue, on or before March 1 of each year, in such form and on such blanks as the department may prescribe and provide, the statement required under ORS 308.520 and 308.525, and shall include therein the amount of all its gross revenue subject to the tax levied by ORS 308.805 for the calendar year preceding the making of such statement. The association shall compute and forward on or before July 1 of each year the lesser of the tax calculated under ORS 308.807 (1) on such gross revenue or the tax calculated under ORS 308.807 (2) on the real market value of the transmission and distribution lines used or operated by the association.

(2) The department shall notify the association of the real market value of the transmission and distribution lines used or operated by the association on or before the date fixed for notices of assessment to be issued under ORS 308.582 or 308.595.