What Changes Your Workers' Comp EMR

Updated September 12, 2026

Most contractors who come to us already understand roughly how the number is calculated. What they want to know is what actually moves it. Not the formula. The specific thing, done differently, that changes the mod. Here are the real levers, in the order they usually matter.

Frequency beats severity

Your workers’ comp EMR (experience modification rate) weights the first slice of each claim’s cost, the primary portion, at full value, and discounts the rest. That means three separate $15,000 claims generally hurt your mod more than one $45,000 claim, because more of the total dollar amount lands in the fully weighted primary slice across three claims than it does in one.

If you’re trying to improve your mod over time, reducing how often claims happen moves the number more than reducing how severe any single claim is, even though severity is what feels more urgent when it happens.

Safety programs aimed at preventing frequent, lower-severity incidents (repetitive strain, minor lacerations, slips) tend to help the mod more, per dollar of prevention effort, than programs aimed only at preventing the rare catastrophic claim. Both matter for reasons that go well beyond the rating. But if you’re asking which one moves this specific number, frequency does.

The medical-only reduction, where it applies

A medical-only claim is one where the injured worker got treatment but never missed work. No lost time, no indemnity payments, just medical bills. Many state rating plans apply a reduced weight to medical-only claims when calculating experience mods, on the theory that a claim with no lost time is less predictive of future risk than one with lost time.

Where your state’s rating plan has adopted NCCI’s Experience Rating Adjustment (ERA), a medical-only claim counts at only 30% of its primary and excess losses, a 70% reduction. Not every state has adopted ERA, so check your current worksheet or ask your agent whether your state’s plan applies it, and if so, whether the reduction was applied to every eligible claim. If a medical-only claim on your worksheet is being valued as if it were a lost-time claim, that’s worth flagging. The difference is not small.

Closing and capping claims

An open claim sits on your worksheet at its reserve, the carrier’s current estimate of total cost, not at what’s actually been paid. A claim that should have closed months ago, but is still carried open at an old reserve, is inflating your mod for no reason connected to actual risk.

Getting a stale open claim closed, or its reserve corrected to reflect where it actually stands, helps whichever of the three ratings this claim touches haven’t been calculated yet. It doesn’t change a mod that’s already been issued: NCCI revises an issued rating, and up to two prior ones, only for ownership or combination changes, not for a reserve correction. The earlier you catch it, the more of those three ratings you still have a chance to affect.

Some states also cap, under NCCI’s per-accident limitation, the amount a single accident can contribute to a mod calculation, and NCCI applies that cap automatically inside the formula. What goes wrong isn’t that the cap gets skipped. It’s that the wrong limitation amount gets used, an outdated figure after a carrier or state change, or the wrong state’s limitation, or that a single accident producing multiple claims doesn’t get grouped under one limitation the way it should. Ask your agent or carrier to confirm the limitation amount and, where more than one claim came from the same accident, that they were combined.

Payroll and class code accuracy

Your expected losses, the baseline your actual claims get measured against, are calculated from your payroll, broken out by class code (the classification system that groups similar operations, like roofing or electrical, for rating purposes). Two things go wrong here often.

Payroll reported to the bureau doesn’t match what you actually paid for that class and period. This is usually an audit correction that never made it into the rating, or a data entry error at the carrier.

Payroll sits under a class code that doesn’t match the work it pays for. A framing crew coded as general labor, for instance, gets measured against the wrong expected-loss baseline entirely.

Neither of these touches a single claim. Both change your mod anyway, because they change the denominator every claim gets compared against.

Ownership changes

When a contracting business is bought, sold, merged, or restructured, combinability rules decide whether the prior entity’s experience mod follows the new entity. Handled correctly, an entity with a clean history doesn’t inherit someone else’s bad claims history, and an entity trying to escape a bad history by restructuring generally can’t.

Handled incorrectly, which happens more often than you’d expect, especially in smaller transactions where nobody involved is a rating specialist, either the wrong history gets carried forward, or a history that should have transferred doesn’t. If your company has changed ownership structure at any point in the last several years, this is worth checking specifically, even if nothing else about your claims looks unusual.

Timing matters more than urgency

Every one of these levers takes effect on the bureau’s schedule, not yours. A payroll correction, a closed claim, a corrected class code: none of it changes your mod the day you fix it. It changes the mod calculated at the next reporting date that includes the corrected data, and depending on where you are in your policy year, that can be months away.

This is why fixing things early matters more than fixing things fast. A correction made right after your current rating is calculated has the most time to matter before the next one. A correction made the week before a reporting deadline may not make it in at all. If you know something is wrong, the useful move is to raise it as soon as you find it, not to wait for a better moment.

What doesn’t move the number

Improving your safety program going forward matters for your business and for future years. It doesn’t touch the current worksheet. The three-year window means today’s changes affect ratings that haven’t happened yet. And talking to your GC about why a claim happened doesn’t change the number on the form. The mod doesn’t carry context. Only a correction to the underlying data does.

Try the free EMR Cost & Bid Check calculator to see what these levers are worth on your specific worksheet, or get on the waitlist for a full verification. It’s a flat fee, no contingency, and the savings are yours.