(1) Except as provided in subsection (2) of this section, the date of receipt of any properly addressed application, report, statement, notice, or payment required to be made under the provisions of this title is the date shown by the post office cancellation mark on the envelope of the submitted material. The provisions of this section do not apply to reports required to be delivered under RCW 29B.25.140 and 29B.50.070.
(2) When a report is filed electronically with the commission, it is deemed to have been received on the file transfer date. The commission shall notify the filer of receipt of the electronically filed report. Such notification may be sent by mail or electronically. If the notification of receipt of the electronically filed report is not received by the filer, the filer may offer proof of sending the report, and such proof shall be treated as if it were a receipt sent by the commission. Electronic filing may be used for purposes of filing the special reports required to be delivered under RCW 29B.25.140 and 29B.50.070.