Reference
How is workers’ compensation actually rated?
The short answer
Premium is broadly payroll multiplied by a class-code rate, adjusted by your experience modifier. Class codes describe the work performed and are frequently wrong; the modifier compares your claims history to expected losses for your class and size, and rewards claim frequency reduction more than severity reduction. Under a PEO, coverage typically moves to the provider’s policy and your own modifier may stop developing — which helps an employer with poor history and can disadvantage one with a good record.
The three inputs
Payroll, by class code. The class-code rate, which reflects the risk of that work in that state. And the experience modifier, which compares your actual claims history to what would be expected for an employer of your class and size.
A modifier below the baseline reduces premium; above it increases premium. Everything an employer can influence sits in the first and third of those.
Class codes are wrong more often than people expect
Codes are assigned by the work performed, not the job title or the industry of the business. Employees doing clerical work inside a manufacturer may belong in a clerical code rather than the manufacturing one, and the rate difference is large.
Codes assigned when a company was smaller and simpler frequently never get revisited as roles change. Reviewing them is one of the more reliably valuable audits available, and it is genuinely unglamorous work.
What the modifier rewards
Frequency more than severity. Several small claims typically damage a modifier more than one large one, because the formula treats frequency as the better predictor of future losses.
That has a practical consequence: reducing minor incidents and managing small claims to closure moves the modifier more than most employers expect, and it is cheaper than the safety investment usually reached for first. Return-to-work programs matter for the same reason — a claim that stays open accrues.
What changes under a PEO
Coverage typically moves onto the provider’s policy, and your employees are rated within a pool. For an employer with an unfavourable modifier, that can be a material improvement. For one with a clean record and a favorable modifier, it can mean giving up an advantage you spent years earning.
There is a longer-term consideration. If your own modifier stops developing while you are in a pool, re-entering the standard market later means being re-underwritten with a gap in your history. That is not a reason to avoid a PEO, but it belongs in the exit analysis rather than surfacing during it.
The audit nobody enjoys
Premium is estimated at binding and reconciled at audit against actual payroll and actual classifications. Poor records at audit tend to produce classification into higher-rated codes by default. Keeping payroll split cleanly by class throughout the year is what makes that audit uneventful.
| Lever | Effect | Effort |
|---|---|---|
| Correct class codes | Often significant | An audit, once |
| Reduce claim frequency | Improves the modifier | Ongoing operational work |
| Return-to-work program | Shortens claim duration | Moderate, sustained |
| Clean payroll split by class | Prevents audit reclassification | Routine discipline |
| Move into a PEO pool | Depends on your modifier | A structural decision |
| Shop the market | Modest without the above | Annual |
Common questions
Can we challenge our experience modifier?
Do we lose our modifier in a PEO?
How often should class codes be reviewed?
Where this sits
This page supports Benefits Administration — the practice that does this work.
