Tennessee to Maryland: master HVAC technician license reciprocity

State contractor route (CMC / CMC-C). Required statewide for projects of $25,000 or more and accepted by the cities as a substitute for their own master cards for permit purposes (Nashville registers CMC/CMC-C firms for $100 with a $40,000 bond and $300,000 liability certificate; Memphis/Shelby County registers state mechanical licensees for $150). Requirements: Business & Law exam plus the CMC-C or CMC trade exam ($50 pre-approval for CMC), $250 application fee, reviewed or audited financial statement or a surety bond of at least 50% of the monetary limit (from July 1, 2026), general liability and workers' compensation insurance. Trade-exam waiver, on verification by the other board that the qualifying agent passed a comparable exam: Alabama HVAC (CMC-C), Louisiana Mechanical (CMC), Mississippi Mechanical (CMC), Ohio HVAC (CMC-C), South Carolina HVAC (CMC-C), West Virginia Mechanical (CMC). The Board stresses the waiver applies only to the trade exam, cannot be used by applicants with discipline, open complaints or felony convictions, and does not allow another state's license to be used in Tennessee.

Nashville (Davidson County). The Board of Mechanical, Plumbing and Electrical Examiners and Appeals issues the Master Mechanical certificate (six years' experience) and HVAC&R certificate (four years); a mechanical engineering degree may substitute. The application asks for licenses held in other cities or states, employer confirmations and a recommendation letter; the Chief Mechanical Inspector approves, Prov administers the exam (70% to pass, 30-day retest wait). The certificate holder then registers the firm as a Metropolitan Mechanical Gas Contractor with a Davidson County business license, $40,000 permit bond and $300,000 liability certificate. No exam waiver for out-of-state licenses is published.

Memphis and Shelby County. First-Class Mechanical Contractor (age 21, 4 years of full-time installation or design experience, unlimited scope) and Third-Class Mechanical Contractor (2 years, equipment up to 15 tons or 15 hp) after a written exam set by the Mechanical/Gas Code Board; $150 registration, $110 annual renewal, licenses expire December 31, $25,000 continuous permit bond. The mechanical code has no reciprocity provision for mechanical contractors.

Chattanooga. Master Mechanical Contractor license from the Board of Mechanical Examiners: three or more years as a Journeyman Mechanic Class 1 or 2, or a current or previously held unrevoked Master Mechanical Contractor or equivalent license from Chattanooga or any other governmental agency, or a Tennessee PE license, or acceptable education and experience; $415 per two-year cycle including the exam fee. A license from elsewhere establishes eligibility for the exam but is not stated to waive it.

Knoxville. Permits are pulled under a State Contractor Registration (CMC/CMC-C) or the other registration types on the city's permit page; the city does not publish its own mechanical license classes and fees online, so contact Plans Review & Inspections (865-215-4311).

Out-of-state holders. The only published recognition in Tennessee is the state Board's trade-exam waiver for contractors from AL, LA, MS, OH, SC and WV, which still requires the Business & Law exam and a full contractor application. The local master cards in Nashville, Memphis and Chattanooga treat an out-of-state master license as evidence of experience or exam eligibility, not as a substitute for their own examinations.