Here is a quote from the rules. If you need further clarification, let me know.

Eligibility

Active and retired firefighters who are, or were members of an organized first responder (Fire-Rescue or EMS) unit anywhere in the world are eligible to compete. A "Team" may be comprised of individuals from the same department, county, fire district or accredited governmental educational agency. If any other organization believes they meet the intent of the criteria, they may submit a written request to the Challenge Team Eligibility Committee for review and approval. Exception to this rule are as follows: Female relay teams, which may consist of members residing any where in the same state, Tandem teams and over 50 Relay teams may consist of members drawn from anywhere.

Eligibility for Non-Municipal Departments and Agencies:


Accredited/licensed private Fire/EMS departments and educational agencies providing Fire/EMS training shall be eligible to assemble a team for competition. Competitors of said teams must provide verifyable proof of current employment/contract service for their organization by providing signed documentation indicating continuing employment (paystub, 1099, w-2) from the accredited/licensed organization. It is the intent of OTC to be inclusive, rather than exclusive, ceasing the practice of “cherry picking” elite competitors that share no common connectivity. If a competitor wishes to challenge the validity of a team or question the legitimacy of their own team, a written appeal must be submitted to OTC and the Challenge Team Eligibility Committee (CTEC).