Michigan Unlicensed HVAC Work Penalties — Fines, Lien Rights, and the $600 Threshold

Michigan Doesn't Have a Gray Area for Unlicensed HVAC Work

Some states let you slide on small residential jobs without a contractor license. Michigan isn't one of them. Under the Skilled Trades Regulation Act (PA 407 of 2016), mechanical work covered by Article 8 and performed for compensation requires the appropriately classified Mechanical Contractor license, regardless of the contract value, subject to narrow statutory exceptions.

That last part catches a lot of technicians off guard. General residential alterations under $600 are exempt from the state's builder licensing requirements, but that $600 threshold explicitly does not apply to specialty trades. An HVAC system replacement worth $400 still requires a licensed Mechanical Contractor.

Criminal Penalties

Operating as an unlicensed mechanical contractor in Michigan violates MCL 339.5601. The statutory penalties escalate by violation count:

• First violation: misdemeanor, fine up to $500 or imprisonment up to 90 days, or both
• Second violation: misdemeanor, fine up to $1,000 or imprisonment up to one year, or both
• Third or subsequent violation: felony, fine up to $25,000 or imprisonment up to five years, or both

These aren't theoretical. Local code enforcement officers and building inspectors actively report unlicensed work. A stop-work order on a job site often triggers the investigation that surfaces the licensing violation.

The Residential Lien Rights Trap

Beyond criminal penalties, working without a required license can strip you of one of the most important legal protections on a residential project: the construction lien.

Michigan's Construction Lien Act does not use the $600 builder-license threshold to define residential lien rights. For a residential project, a contractor must satisfy the written-contract and disclosure requirements in MCL 570.1114, and a contractor required to be licensed for the work must be licensed.

But here's the catch: under Michigan statute, an unlicensed contractor cannot enforce a construction lien on a residential project when a license was required. If you complete a $15,000 furnace and ductwork installation without holding the proper Mechanical Contractor license, and the homeowner refuses to pay, you cannot enforce that lien. A claim to recover for work requiring a license also requires you to allege and prove proper licensure.

This isn't just a penalty — it's a financial death sentence for a small operator. One unpaid job without lien protection can wipe out months of profit.

Stop-Work Orders and Double-Fee Penalties

When a local building inspector discovers unpermitted or unlicensed work, the enforcing agency gives written notice and an opportunity to show cause. If the person doing the construction fails to appear and show good cause within one full working day after notice is delivered, the agency posts a stop-construction order. The project then halts until the licensing issue is resolved.

In most Michigan municipalities, the contractor of record must then:

1. Obtain the proper license and registration
2. Apply for the permits that should have been pulled before work started
3. Pay the original permit fees plus a penalty fee — many jurisdictions charge double the standard permit cost for work started without authorization
4. Schedule inspections for any work that was completed before the stop-work order

Failed inspections after a stop-work order carry their own re-inspection fees, typically $50 per visit. And if the unlicensed work crossed into electrical or plumbing territory (connecting line-voltage power or potable water), those violations compound with separate trade-specific penalties.

The "Side Job" Risk

The most common path to an unlicensed-work charge is the technician who does side jobs on weekends. They hold an EPA Section 608 certification, they work for a licensed company during the week, and they assume that's enough to take on a furnace swap for a friend's neighbor.

It isn't. An EPA 608 certification is a federal environmental credential for handling refrigerants. It carries no Michigan authority to contract independently or pull a mechanical permit. Those activities require an appropriately classified state Mechanical Contractor license, subject to narrow statutory exceptions such as the owner-occupant exemption.

The trigger is usually a building department complaint, a neighbor dispute, or a warranty claim that reaches an inspector. By the time the violation is flagged, the technician is facing both criminal exposure and the loss of any payment they expected.

How to Get Licensed the Right Way

Michigan's mechanical licensing process generally requires three years or 6,000 hours of documented experience per classification, with statutory pathways for equivalent, military, and limited education credit, a passed PSI examination, and registration with your local building department. The Michigan HVAC License Guide lays out every step of the compliance pathway — from experience affidavit formatting to municipal registration — so you can transition from employee to licensed contractor without the legal risk of operating in the gap.

See more Michigan guides →