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Workers comp premiums feel like they come out of nowhere. Your agent quotes a number, the auditor adjusts it later, and the math behind it is a mystery. It does not have to be. Almost the entire premium comes down to one thing: your class codes.
What a class code is
A class code is a four-digit number that describes the type of work your employees do and the risk that comes with it. Every code has a rate, expressed as dollars of premium per $100 of payroll. Insuring a bookkeeper is cheap. Insuring a roofer is not, because roofers get hurt more often and more seriously.
The codes describe the nature of the work performed, not the job title on your org chart. A person your company calls a “project coordinator” who spends every day at a desk doing data entry is a clerical employee, not whatever the internal title says. That distinction is where a lot of money gets lost.
The formula
The basic premium calculation is straightforward: take your payroll, divide by 100, and multiply by the class rate. Then multiply by your experience modification factor, which adjusts the number up or down based on your claims history. So the formula is:
(Payroll / 100) x class code rate x experience mod = premium
Example: $300,000 of payroll in a class rated at $2.00 per $100, with a 1.0 mod, costs $6,000 a year. The same payroll in a class rated at $0.40 costs $1,200. The code is doing almost all of the work in that difference.
Who sets the codes
In most states, the National Council on Compensation Insurance (NCCI) sets the classification system. Thirty-five states plus the District of Columbia use the NCCI system. Eleven states run their own rating systems, and four states (North Dakota, Ohio, Washington, and Wyoming) run monopolistic state funds where coverage must be bought from the state rather than a private carrier. If you operate in multiple states, each state’s system applies to the payroll in that state.
A few codes show up everywhere. Clerical office employees are NCCI code 8810, one of the cheapest. Outside salespeople are 8742. Full-service restaurants are 9082. These two or three codes cover a huge share of small-business payroll, and getting even one of them wrong moves the premium meaningfully.
How wrong codes cost you
Misclassification usually goes one of two ways. The expensive way: your desk workers get lumped into a higher-rated operational code, and you overpay for years without knowing it. The painful way: the carrier’s auditor reclassifies your workers into a higher-rated code at the annual audit, and you get a surprise bill for the difference. Published guidance from classification experts notes that codes like 8810 and 8742 are among the most frequently reclassified, which tells you how often employers get this wrong.
The annual workers comp audit exists to reconcile estimated payroll against actual payroll by code. Keeping payroll records separated by classification code throughout the year, instead of scrambling at audit time, is the single most effective thing you can do to avoid surprises. We covered the audit process in detail in our guide to workers comp audits.
What to check on your policy
Pull out your current policy and look at the classification section. For each code listed, ask: does this describe what these employees actually do all day? Common fixes: splitting clerical and sales staff out of operational codes, making sure remote workers are coded for the work they do rather than the work the company does, and confirming that owners and officers who are excluded are actually excluded (rules vary by state).
Rates also vary by industry and state, sometimes dramatically. A restaurant might pay $1.50 to $4.00 per $100 of payroll depending on the state and the operation. Our guide to workers comp costs by industry has more of those benchmarks.
Talk to your agent before renewal
Class codes are one of the few parts of an insurance premium you can actively manage. Review them with your agent before every renewal, especially after you hire new roles, change what people do, or add a location. It is a thirty-minute conversation that regularly saves businesses real money, and most owners never have it.
