Colorado Revised Statutes Title 39. Taxation § 39-21-105.5. Notice--first-class mail--definition

(1) Except as provided in subsection (2) of this section, any notice required to be given to any taxpayer pursuant to the scope of this article as set forth in section 39-21-102 is sufficient if mailed, postpaid by first-class mail to the last-known address of the taxpayer. The first-class mailing of any notice pursuant to the scope of this article as set forth in section 39-21-102 creates a presumption that such notice was received by the taxpayer if the department maintains a record of the notice and maintains a certification that the notice was deposited in the United States mail by an employee of the department. Evidence of the record of the notice mailed to the last-known address of the taxpayer as shown by the records of the department and a certification of mailing by first-class mail by a department employee is prima facie proof that the notice was received by the taxpayer.

(2) Notwithstanding subsection (1) of this section, and notwithstanding any other provision of law that requires written correspondence to be sent by first-class mail to a taxpayer, the department may promulgate rules to establish procedures that allow a taxpayer to voluntarily elect to receive any notice or other communication by electronic means pursuant to the established procedures. The procedures must be designed to ensure that to the greatest degree reasonably possible the party viewing the notice or communication is the taxpayer for whom the notice or communication is intended. An electronically transmitted notice or communication is sufficient to satisfy any requirement of mailing if sent in accordance with the procedures. If the department maintains a record of the recipient viewing the notice or communication, the record creates a presumption of receipt by the taxpayer and is prima facie proof that the notice or communication was received by the taxpayer.

(3) For purposes of this section, the term “taxpayer” includes the agent or personal representative of the estate of the taxpayer.