The Colorado Department of Revenue implements a highly collaborative process when developing regulations. The Department may assemble work groups made up of stakeholders and subject matter experts to deliberate and provide direction and guidance for the proposed language with which to begin its formal rulemaking process.
In this process, the proposed rules are published and members of the public are encouraged to provide comment and concerns regarding the proposed rule language. Public comment can be made in writing, in testimony during a public hearing, or both. Upon completion of the public comment period a Hearings Officer (who also conducts the public hearing sessions) reviews the public comments and makes a recommendation to the Executive Director of the Department of Revenue, or their designee, who then adopt the rules as proposed, adopts rules with modifications or sends the rules back for additional work.
Please see below links to specific rulemaking information for each of the Divisions within the Department of Revenue. 
Enforcement Division: