Overview
Tennessee does not issue a standalone HVAC license. It runs HVAC through its contractor licensing system, and one number decides which rules apply to you: $25,000. At or above that figure on a single project, counting both labor and materials, you need a state contractor license with the Mechanical classification, known as CMC. That license carries a monetary limit, the largest single project you can take, which is calculated from a CPA-prepared financial statement rather than from any test score. The Tennessee Board for Licensing Contractors, housed in the Department of Commerce and Insurance, issues and governs it. Below $25,000, a lighter limited-licensed path or local registration may cover the work instead. Separately, and on top of all of this, federal law requires EPA Section 608 certification for anyone who handles refrigerant. So three things gate Tennessee HVAC: the $25,000 threshold that triggers the contractor license, the financial statement that sets your project ceiling, and EPA 608 for refrigerant. This guide breaks down each one. Rules and dollar figures shift, so read the board's current classification outline and forms alongside this.
The Mechanical (CMC) Classification
Tennessee files HVAC under Mechanical because the state treats heating, cooling, and the piping that feeds them as one trade family. The full Mechanical classification, CMC, is broad. Its subcategories cover plumbing and gas piping, process piping, HVAC and refrigeration, sprinklers and fire protection, mechanical insulation, pollution control, pneumatic tube systems, temperature controls, and boiler construction and repair. A full CMC holder can do the whole spectrum. Most HVAC contractors do not need that range. They take CMC-C, the HVAC, refrigeration, and gas piping subcategory, which maps directly to what a heating and cooling business actually does. The trade-off is scope: CMC-C lets you install and service comfort cooling, refrigeration, and the gas piping that serves them, but not the full plumbing or process-piping work a complete CMC allows. The full CMC requires board pre-approval before you can sit for the exam; CMC-C does not. Pick the narrowest classification that covers your real work, because a wider one means a harder exam and more pre-approval steps for capabilities you may never use. The board's classification outline lists each subcategory's exact scope.
The Monetary Limit
The CMC license does not let you take a job of any size. It carries a monetary limit, the maximum dollar value of a single project, and that number comes from your finances, not your exam. Tennessee sets the limit at roughly ten times the lesser of your working capital or your net worth, drawn from a financial statement an independent CPA prepares. A contractor showing $50,000 in both working capital and net worth lands near a $500,000 limit. Want bigger jobs? Show stronger financials. The state's logic is that a larger project needs a larger cushion to absorb cost overruns and finish the work, so it gates job size on financial capacity rather than on passing a multiple-choice test. The statement type scales with the limit you are requesting: a reviewed statement covers limits of $3,000,000 or less, while anything above that requires the more rigorous and costly audited statement. This is the part new HVAC contractors underestimate most. A CPA engagement carries real lead time and expense, and how cleanly your balance sheet is presented directly sets the ceiling on the work you can legally bid.
Exams, Experience, and Financials
Getting the CMC license stacks several requirements. First, the trade exam for your mechanical classification, covering HVAC, refrigeration, and the relevant codes, administered through the state's testing vendor, PSI. Second, the Business and Law exam that every Tennessee contractor classification requires; it is open-book off the NASCLA contractor's guide and runs Tennessee-specific rules on contracts, liens, and project management, so general trade knowledge alone will not carry you. Third, the CPA-prepared financial statement, reviewed or audited, that sets your monetary limit. Fourth, the insurance the board expects, general liability and, where you have employees, workers' compensation. And running underneath all of it, federal EPA Section 608 certification for any refrigerant handling. The full CMC also requires board pre-approval of your experience before you test; CMC-C does not gate testing the same way. Sequence matters: line up the CPA engagement early, because the financial statement is slower and pricier than booking an exam slot. Check the current exam list, score requirements, and insurance minimums against the board's published bulletin, since those details get adjusted.
EPA 608 and Refrigerant
EPA Section 608 is a federal certification, separate from anything Tennessee issues, and it is mandatory for anyone who opens a refrigerant circuit. You can hold a perfectly valid CMC license and still be breaking federal law if you service a system without it. There are four flavors. Type I covers small appliances charged with less than five pounds of refrigerant. Type II covers high-pressure equipment, which is most residential and commercial split systems and heat pumps. Type III covers low-pressure equipment like large building chillers. Universal rolls all three into one credential, and it is the practical choice for a tech who wants to work on anything. To earn any of them you pass a Core section plus the type-specific section through an EPA-approved certifying organization. The certification is lifetime; once you hold it, there is no renewal or continuing education. For a Tennessee HVAC business this is the cheap, easy gate compared with the license, often under a hundred dollars, so there is no reason for any technician touching refrigerant to skip it. Treat 608 as table stakes that sits on top of your state license, not a substitute for it.
The Application Process
The sequence runs in a specific order, and getting it wrong wastes weeks. First, study for and pass the two exams through PSI: the mechanical trade exam for CMC or CMC-C and the Business and Law exam. If you are going for the full CMC, get the board's pre-approval of your experience before you can test. Second, engage a CPA to prepare your reviewed or audited financial statement, since the number it produces sets the monetary limit you will request, and this is the slowest piece, so start it in parallel with exam prep. Third, assemble the application to the Tennessee Board for Licensing Contractors with the financial statement, exam results, insurance, references, and the entity details in the exact name you will operate under. The board reviews applications on a schedule, then issues the license with the CMC or CMC-C classification and your monetary limit attached. Fourth, handle EPA 608 on its own track through an approved testing organization, independent of the state timeline. You can knock out 608 anytime. Local jurisdictions may also want their own registration or permits on top, so check the city or county where you will be working before you pull permits.
FAQ
Do I need a Tennessee contractor license for all HVAC work? No. The contractor license with the Mechanical (CMC) classification is required at or above $25,000 on a single project, counting labor and materials. Below that, a limited-licensed path or local registration may cover you, but the threshold is the trigger.
What is the difference between CMC and CMC-C? Full CMC covers the whole mechanical spectrum, including plumbing and process piping, and requires board pre-approval to test. CMC-C is the HVAC, refrigeration, and gas piping subcategory most heating-and-cooling businesses actually need, and it does not gate testing the same way.
How is my project size limit set? By a CPA-prepared financial statement, roughly ten times the lesser of your working capital or net worth. A reviewed statement covers limits up to $3,000,000; above that you need an audited statement.
Is EPA 608 part of the Tennessee license? No. EPA Section 608 is a separate federal certification required for anyone handling refrigerant. You need it on top of the state license, and it is lifetime once earned.