Your workers’ comp premium is built directly from payroll: for each job classification, the insurer takes your reportable payroll, divides by 100, multiplies by the rate assigned to that classification code, and then multiplies by your experience modification factor. That means how payroll affects your workers’ comp premium comes down to three things you can actually influence — what dollars you report as payroll, which classification code each dollar sits under, and how accurate your reporting is when the auditor arrives.
The Formula, With Numbers
Take total payroll for a classification, divide by 100, multiply by the class rate, multiply by your experience mod. If you have $500,000 in payroll under a classification rated at $1.50 per $100 and your experience mod is 1.0, the premium for that classification is $7,500. A business with multiple job types runs this calculation for each classification code on the policy and adds the results.
Rates vary enormously between codes. Clerical work might sit well under $1.00 per $100 of payroll; roofing or structural steel work can run above $20.00 per $100. Because the spread is that wide, every dollar you report and every code you assign it to has a direct, measurable effect on the bill.
What Counts as Payroll
Payroll for workers’ comp purposes is broader than what shows up on a paycheck. The NCCI Basic Manual defines it as money or substitutes for money paid to employees, starting from gross pay before deductions for taxes, benefits, or retirement contributions.
On top of base wages, these get added:
- Commissions, including draws against future commissions.
- Bonuses, whether performance-based, stock, or other incentive pay.
- Holiday, vacation, and sick pay, even though no work is performed during those hours.
- Piecework and other output-based pay, in full.
- The fair market value of housing, lodging, or meals provided as part of the pay arrangement.
Overtime follows a specific rule that’s worth getting right. Only the straight-time portion of overtime wages counts toward premium. The extra pay above the regular hourly rate is excluded, but only if your records break out overtime pay separately by employee and by classification. Lump it into total pay and you lose the deduction. For time-and-a-half recorded as a single combined amount, one-third of that combined figure is excluded; for double-time, half is excluded.
What Doesn’t Count
Several categories are excluded from premium, and having your records reflect them cleanly is what makes the exclusion stick:
- Employer contributions to group health insurance, retirement plans (including 401(k) matching), Section 125 cafeteria plans, and health savings accounts.
- Tips and gratuities that customers pay directly to the employee rather than through you.
- Business expense reimbursements — travel, mileage, and similar — as long as your records document them as legitimate expenses. If you can’t verify them, the auditor treats them as payroll.
- Severance pay to departing employees, other than accrued vacation payouts.
One distinction trips people up constantly: employee-authorized salary reductions for retirement or cafeteria plans are still reportable payroll. The exclusion covers your contribution as employer, not the portion the employee directs out of their own gross pay. Miss this in either direction and the audit will find it.
Splitting Payroll Across Classification Codes
Every type of work is assigned a four-digit classification code with its own rate, and a single business can easily carry five or more codes on one policy.1NCCI. NCCI Classification Research – Top Reclassified Codes in 2023 The code that produces the largest share of your payroll (excluding standard exceptions like clerical staff, drivers, and outside salespersons) is your “governing classification.”2NCCI. Heterogeneity of Office and Clerical Classifications
Standard exception employees get their own lower-rated codes only when your records clearly document the hours they spend in those roles. If an employee who mostly does clerical work also visits job sites or handles inventory in a warehouse, and you can’t show a clean time split, their entire payroll gets assigned to the higher-rated governing code.
This is where record-keeping pays. To divide an employee’s payroll between two classifications, you need time records that show hours in each role. Without them, the insurer assigns all of that employee’s payroll to whichever applicable code carries the higher rate. When there’s a large gap between your clerical rate and your governing rate, sloppy timekeeping can quietly add thousands of dollars a year to your premium.
Owner and Officer Payroll
Owners and corporate officers follow rules that don’t apply to regular employees. In most NCCI states, executive officers of a corporation are automatically included in coverage, and their payroll is assigned within a fixed minimum-to-maximum range regardless of what they actually earn. For 2026, those NCCI limits are $73,996 at the minimum and $295,984 at the maximum. An officer earning $400,000 has $295,984 counted toward premium; one earning $50,000 is bumped up to $73,996.
Sole proprietors, general partners, and LLC members are treated differently. They’re usually excluded from coverage by default and must elect to be included. When they opt in, a flat assigned payroll is used rather than their actual earnings. For 2026, that assigned amount is $58,200 in NCCI states.
Many states let corporate officers formally opt out of coverage by filing an exclusion form. This removes them from the payroll calculation entirely and can meaningfully cut premium at small corporations where officer pay is a large slice of total payroll. The tradeoff: an excluded officer injured on the job has no workers’ comp benefits. Thresholds and rules vary by state, so confirm the figures with your rating bureau or insurer.
Subcontractors Can Become Your Payroll
If you hire a subcontractor who doesn’t carry their own workers’ comp coverage, the auditor will add what you paid that sub to your reportable payroll. From the insurer’s standpoint, an uninsured sub creates the same injury exposure as an employee, and if the sub gets hurt, your policy is on the hook.
The prevention is straightforward: collect a valid certificate of insurance from every subcontractor before work starts, and keep it on file for the audit. No certificate means the auditor treats those payments as your payroll, classified under the code for the work performed. For contractors who use subs regularly, this single issue can generate the largest adjustment on the entire audit.
When the sub does carry coverage, you can typically remove their payments from your auditable payroll entirely. If the certificate is missing but you can document labor separately from materials, only the labor portion may be added, though this varies by insurer and state. The safe practice is never to let a sub start work without a current certificate on file.
The Year-End Audit
Every workers’ comp policy includes an audit. After the policy term ends, the insurer compares your actual payroll records against the estimates that set your premium. Expect the auditor to ask for Form 941 quarterly returns, W-2s, general ledgers, payroll journals, and certificates of insurance for every subcontractor. Payments reported on 1099-NEC forms get particular attention to confirm the subs carried their own coverage.
If actual payroll came in above the estimate, you’ll get an additional premium bill. If it came in below, you’ll get a refund or credit toward the next term.
Refusing to cooperate is one of the more expensive mistakes available. Insurers can impose an audit noncompliance charge equal to up to twice your estimated annual premium, and noncompliance can lead to cancellation and difficulty getting coverage elsewhere until the audit is resolved. When the notice arrives, treat it as a priority.
Payroll’s Effect on Your Experience Mod
Your experience modification factor, or e-mod, is the multiplier at the end of the formula, and it’s also driven by payroll. The calculation compares your actual losses to your expected losses, and expected losses are computed from your payroll and classification codes.3NCCI. ABCs of Experience Rating A $2 million payroll is expected to generate more claims than a $200,000 one in the same industry, so the baseline scales with size.
An e-mod of 1.0 is average for your size and industry. Below 1.0 lowers your premium; above 1.0 raises it. The calculation pulls three years of historical data, excluding the most recent year, so payroll you report today feeds into the e-mod that applies to your policy two or three years out.
That lag is why accuracy matters beyond the current bill. Overstating payroll inflates expected losses and can make your e-mod look artificially low, until an audit corrects the numbers and it recalculates. Understating has the opposite effect and can produce an unexpectedly high modifier later. Consistent, accurate reporting keeps the whole system honest and your premium predictable.