Section 16-4-301 - When documents deemed filed(a) Any report, claim, tax return, statement or other document or any payment required or authorized to be filed or made to the state of Wyoming or to any political subdivision thereof, which is: (i) Transmitted through the United States mail, shall be deemed filed or made and received by the state or political subdivisions on the date shown by the post office cancellation mark stamped upon the envelope or other appropriate wrapper containing it; (ii) Mailed but not received by the state or political subdivisions or where received and the cancellation mark is illegible, erroneous or omitted, shall be deemed filed or made and received on the date it was mailed if the sender establishes by competent evidence that the report, claim, tax return, statement or other document or payment was deposited in the United States mail on or before the date for filing or paying. (b) In cases of nonreceipt of any report, tax return, statement or other document or payment required by law to be filed or made, the sender shall file with the state or political subdivision a duplicate within thirty (30) days after written notification is given to the sender that the state or political subdivision did not receive the report, tax return, statement or other document or payment or paragraph (a)(ii) of this section does not apply.