Class code 5537 covers heating, ventilation, air conditioning, and refrigeration work — a core trade class combining ladder work, heavy equipment handling, and year-round service exposure.

Who falls under 5537

HVAC and refrigeration contractors: residential and commercial installation, service and repair work, ductwork in many states.

Common misclassification traps

Boundaries with sheet-metal shop work (fabrication may belong in a shop class), electrical work performed by HVAC techs, and new-construction versus service splits in some state systems. As with every trade: uninsured 1099 helpers become your payroll at audit at this class’s rate.

Rate context

5537 typically runs mid-to-high single dollars per $100 of payroll depending on state — a serious but manageable trade rate where mods and payroll splits (installers versus office versus shop) decide the real number. See our guide to how premiums are calculated for the full mechanics.

Related codes

3169/shop fabrication codes by state, 5190 (electrical wiring), 5645 where residential construction carpentry mixes in, 8810 for office payroll.

Class code 5537 FAQs

What does class code 5537 cover?

HVAC and refrigeration installation, service, and repair — residential and commercial — with ductwork included in many states.

What’s the biggest misclassification risk with 5537?

Shop fabrication payroll belonging in shop classes, and uninsured 1099 helpers charged back at 5537 rates. Clean splits between field, shop, and office payroll protect the premium.

What does 5537 cost per $100 of payroll?

Mid-to-high single dollars per $100 of payroll by state. Field/shop/office payroll splits and mod management set where you land in the range.

Can one business use multiple class codes?

Usually, yes — most businesses have an office/clerical component (8810) alongside their governing class, and payroll can often be split when records support it. Done correctly, splitting payroll across codes is one of the most reliable premium reductions available. Done sloppily, it’s an audit dispute.

Not sure your operation is classified correctly? Misclassification runs both directions — some businesses overpay for years, others build audit bombs. Have us review your class codes, or browse the full class code guide.