Most contractors treat the CNESST as a bill that just arrives. But the number on that bill is set by a classification you can check — and often the single biggest thing standing between you and a lower premium is being in the right class for the work you actually do.
What the CNESST premium is
Every Québec employer registers with the CNESST and pays a premium that funds workers’ compensation — wage replacement and care when someone is hurt on the job. Construction is a higher-risk, higher-rate sector, so for a building business this is a real line item, not a rounding error.
Classification units drive the rate
The CNESST sorts your business’s activities into one or more classification units. Each unit has a rate expressed as dollars per $100 of insurable wages — so a rate of, say, $5.00 means $5 of premium for every $100 of covered payroll. The construction sector runs across units 80020 to 80250, and the unit you’re in reflects the kind of work: framing, roofing, electrical, excavation and so on don’t all carry the same rate.
How the premium is calculated
At its simplest, your premium is:
insurable wages × your rate ÷ 100
with each worker’s insurable wages counted only up to a maximum insurable amount set each year. Larger employers can also get a personalized (risk-adjusted) rate instead of the flat unit rate — your own claims history pushes it up or down.
If you do more than one kind of work
Few contractors do just one thing. When your business spans several activities, you split each worker’s wages across the relevant units based on the time they actually spend on each kind of work — and you have to be able to show that split. This is where clean payroll records matter: if you can’t substantiate how time was divided, the CNESST can put all the wages in your highest-rate unit, and you overpay.
The quiet cost of the wrong class
Classification errors rarely announce themselves. Being slotted into a higher-rate unit than your work warrants, or failing to split multi-activity wages, means a premium that’s too high — every year, until someone checks. The fix starts with payroll that ties hours to activities, filed on your annual Statement of Wages. We keep construction payroll so your CNESST wages and splits are defensible — see construction payroll & the CCQ and contractor bookkeeping, or talk to us. General information, not advice for your business; confirm your classification and the current rates with the CNESST.
Frequently asked questions
How is a CNESST premium calculated?
Roughly, insurable wages multiplied by your classification unit’s rate, divided by 100 — with each worker’s wages counted up to a yearly maximum insurable amount. Larger employers may have a risk-personalized rate.
What are the construction classification units?
The construction sector falls within CNESST units 80020 to 80250. The specific unit reflects the type of work, and different trades carry different rates.
We do several trades — how are wages handled?
You split each worker’s wages across the relevant units based on the time actually spent on each activity, and you must be able to support the split. Without records, wages can be assigned to your highest-rate unit.
Sources
- CNESST – Classification of employers and insurance premium
- CNESST – Statement of Wages guide (swguide)
- CFIB – Registering with the CNESST: your number one obligation