You ran a clean year. Zero claims. Nobody got hurt. You kept your crews in line, invested in safety training, and did everything right. Then your experience modification rate comes back and it is still sitting at 1.0. Maybe it even went up. It feels like the system is broken, and honestly, the frustration is justified. But the EMR formula was never designed to reward a single clean year the way most contractors expect. Understanding why requires digging into how the formula actually works under the hood.
How the EMR Formula Actually Works
The experience modification rate is calculated by the National Council on Compensation Insurance (NCCI) in most states, or by an independent state rating bureau in monopolistic states like Ohio. The formula compares your actual losses to the expected losses for a company of your size doing your type of work. If your losses match expectations, you get a 1.0. If they are lower, you go below 1.0. If they are higher, you go above.
What trips up most roofing contractors is the concept of expected losses. The formula does not simply look at whether you had claims. It calculates what a typical roofing company with your payroll volume should experience in losses, then weights those expected losses using a split between primary and excess components. Primary losses carry more weight in the formula because they represent claim frequency, which actuaries consider a better predictor of future losses than severity.
The experience period covers three years of data, excluding the most recent policy year. So if your current policy renews in January 2027, your EMR is based on policy years ending in 2026, 2025, and 2024. That lag means a clean year today will not show up in your mod for another 12 to 24 months depending on your renewal timing.
Here is the part that catches small contractors off guard: the formula uses a ballast value (also called the weighting value) that effectively anchors your mod closer to 1.0 when your premium volume is small. The less premium you generate, the more the formula assumes your loss experience is not statistically credible, and the more it pulls your mod toward the industry average.
Why Small Roofing Companies Get Stuck at 1.0
If your annual workers compensation premium is under $15,000 to $20,000, you are working with a very small experience rating base. The NCCI formula gives your actual experience less weight and the expected losses more weight. In practical terms, even if you had zero claims for three straight years, your mod might only drop to 0.94 or 0.95 instead of the 0.70 or 0.75 you were expecting.
Roofing carries some of the highest expected loss rates in construction. Class codes like 5551 (roofing) have expected loss rates that can run $15 to $25 per $100 of payroll depending on the state. When the formula expects you to have significant losses and you have none, it still tempers the credit because of the small sample size. The system treats your three clean years as possibly lucky rather than indicative of a genuinely safer operation.
Compare that to a roofing company running $2 million in annual payroll. Their premium volume makes them experience-rated with much higher credibility. Three clean years for that company might push the mod down to 0.72 or lower because the formula trusts the data more. The math is not fair to small operators, but it is actuarially consistent.
Another factor that keeps small companies pinned near 1.0 is the minimum mod. Some state rating bureaus set a floor that prevents companies below a certain premium threshold from going below a specific mod. You might be eligible for experience rating but effectively locked into a narrow band around 1.0.
The Fastest Path Below 1.0
If you want to move the needle on your EMR, here is what actually works:
- Grow your payroll base. More W-2 payroll means more premium, which means more credibility in the formula. As counterintuitive as it sounds, adding employees can give your clean record more statistical weight and push your mod lower.
- Close open claims aggressively. Open claims with reserves still count against you. Work with your carrier to close out old claims, even if it means settling for a small amount. A closed claim with a $5,000 payout hurts less than an open claim with $25,000 in reserves.
- Challenge reserve levels. If a carrier is holding $50,000 in reserves on a claim that realistically will settle for $12,000, request a reserve review. Reserves directly impact your mod calculation during the experience period.
- Separate frequency from severity. The EMR formula penalizes claim frequency more than claim severity. One $100,000 claim hurts your mod less than five $20,000 claims. Focus your safety program on eliminating the types of incidents that happen repeatedly: falls from ladders, cuts, sprains from material handling.
- Use a return-to-work program. Getting injured workers back on light duty quickly reduces the total incurred cost of a claim, which directly lowers the primary loss component in the EMR calculation.
Timing matters too. Since the formula drops the oldest year and adds the most recent year as it rolls forward, a particularly bad year falling off the experience period can produce a dramatic improvement. Talk to your agent about projecting your mod forward so you know when that relief is coming.
When a Bad Mod Is Worth Disputing
Not every high mod is a math error, but disputes are worth pursuing more often than most contractors realize. The most common successful disputes involve:
Incorrect payroll classification. If your clerical or sales staff payroll was lumped into a roofing class code, it inflates your expected losses and skews the formula. Getting those employees properly classified into lower-rated codes can change the expected loss calculation and move your mod.
Claims that belong to subcontractors. If a sub's injury was charged to your policy because they lacked coverage, and you can retroactively document that the sub had their own workers comp policy at the time of the incident, you may be able to get the claim transferred off your experience.
Duplicate claim reporting. It happens more than you would think. The same incident gets reported under two claim numbers, or a medical-only claim gets coded as a lost-time claim. Each of these errors inflates your mod.
Clerical errors on the unit stat report. Carriers report your loss data to NCCI via unit statistical reports. Transposition errors, incorrect valuation dates, and wrong class code assignments on these reports are all disputable. Your agent can request a copy of the unit stat data that was used to calculate your mod and compare it against your actual loss runs.
To file a dispute, you or your agent submits a request to NCCI or your state rating bureau with documentation supporting the correction. Turnaround is typically 30 to 60 days, and if the dispute is successful, the corrected mod applies retroactively to the beginning of the policy period. That means you may get a premium refund as well.
The bottom line: the EMR system was designed for large employers with enough data to be statistically meaningful. Small roofing companies are at a structural disadvantage, but understanding the formula gives you the ability to work within it rather than just accepting whatever number shows up on your worksheet. Talk to an agent who specializes in contractor insurance and have them pull your NCCI worksheet apart line by line. That is where the real savings hide.