Your experience modification rate (EMR, or "mod") is a multiplier applied to your workers' compensation premium. It compares your company's actual claim costs with what similar businesses in your industry were expected to have. A mod of 1.00 is average. Below 1.00 you pay less than the baseline rate, and above 1.00 you pay more.
This guide explains what goes into the number, walks through the calculation, shows where to get your official mod, and covers what you can do to move it.
TL;DR
- The EMR is a ratio of your actual losses to expected losses, usually over the latest three years of audited payroll and claims.
- A mod of 1.00 is neutral. A 1.25 mod raises your manual premium by 25%, and a 0.75 mod lowers it by 25%.
- Small employers get a built-in cushion, so one claim cannot swing the number as far as it would for a large company.
- Online calculators are good for what-if planning, but only the rating bureau (or the state agency) publishes the official mod.
- Ownership changes, misclassified payroll and open claims are the most common reasons a mod turns out wrong.
Table of Contents
- What an experience modification rate actually measures
- What the number means in dollars
- How the experience modification rate is calculated
- Where to find your official mod
- Why your mod might be wrong
- How to bring your mod down
- Our perspective: the mod is a conversation, not a verdict
- Who feels the mod most
- Get a second opinion before renewal
- Frequently asked questions
- Sources
What an experience modification rate actually measures
Workers' compensation premiums start with a manual premium: your payroll in each class code, multiplied by the rate for that class. That price treats every roofer or every bookkeeper the same. The experience modification adjusts it for your own track record.
According to NCCI, the experience period generally covers 36 months of data, though it can be shorter or longer (from under 12 months to 45 months) depending on policy terms and whether the business is new. Experience rating is mandatory for eligible employers. NCCI describes it as giving employers a financial incentive to manage workplace safety, because they can influence their own premiums by reducing losses.
Two things to keep in mind:
- The mod looks backward but is used to predict forward. Washington's Department of Labor & Industries describes its experience factor as a prediction of how a business's future claim costs will compare with its risk classification.
- It is about cost, not just frequency. Actual losses are the medical and indemnity costs of claims, so one severe injury can matter more than several minor ones.
What the number means in dollars
The mod multiplies your manual premium. NCCI's own example uses a $100,000 manual premium: a 0.75 mod brings it to $75,000, and a 1.25 mod raises it to $125,000.
| Mod | Label | Effect on a $100,000 manual premium |
|---|---|---|
| 0.75 | Credit mod | $75,000 |
| 1.00 | Neutral | $100,000 |
| 1.25 | Debit mod | $125,000 |
That $50,000 gap between the best and worst rows is for the same payroll and the same industry. The only difference is claim history.
The mod is not the whole bill. Insurers apply their own filed rates, discounts and state-specific charges on top. In Nebraska, for example, the insurance department notes that carriers file a loss cost multiplier, and it allows multipliers between 1.00 and 1.80. The mod is one factor in a chain, but it is the one you can influence most directly.
How the experience modification rate is calculated
The exact formula is set by each rating bureau's plan manual, and details such as thresholds change from year to year. The logic is the same across the bureaus, though.
Step 1: Gather payroll by class code
The bureau takes the audited payroll for each class code during the experience period. Each class has an expected loss rate (ELR) and a D-ratio. The bureau's calculator instructions show these as the inputs for each year and class: payroll, ELR and D-ratio.
Step 2: Work out expected losses
Payroll divided by 100, then multiplied by the class's expected loss rate, gives expected losses for that class and year. Add up all classes and years. The D-ratio splits that total into expected primary losses (the first dollars of each claim) and expected excess losses.
Step 3: Total your actual losses
Actual losses are the medical and indemnity costs of claims in the period. WCIRB explains that the mod is calculated by comparing these actual losses to expected losses once the business is found eligible. Actual losses are also split into primary and excess pieces.
Step 4: Apply weighting and ballast
A plain ratio of actual to expected losses would be unreliable for a small employer, since one random event would dominate the result. So rating plans use two stabilizers:
- Weighting (W): gives less weight to excess losses for smaller employers. WCIRB's guidance covers this weighting approach so a single event does not disproportionately penalize a small business.
- Ballast (B): a stabilizing element that keeps a single unusually large or small loss from causing extreme swings from one year to the next.
Washington explains the same idea with a baseball analogy. A hitter with a .500 average after six at-bats tells you little, while a .300 average over 3,000 at-bats tells you a lot. The more experience a business has, the more weight its own losses get.
Step 5: Divide
In the NCCI-style structure, the mod comes from a ratio shaped like this:
Mod = (actual primary + W × actual excess + (1 − W) × expected excess + ballast) ÷ (expected losses + ballast)
If your actual losses equal what was expected, the mod lands at 1.00. Fewer losses push it under 1.00. More push it above.
A simple illustration
These figures are invented to show the direction, not a real calculation. Suppose two landscaping companies each have expected losses of $80,000 over the period and the same ballast. Company A had $40,000 in actual losses and Company B had $120,000. Company A's ratio comes out below 1.00 and Company B's above it. Neither lands at 0.50 or 1.50, because ballast and weighting pull both results toward 1.00. That is by design.
A payroll note: because the mod depends on audited payroll, how wages are recorded matters. Owners of S corporations who also draw wages may want to review how reasonable owner compensation is set with their accountant, then confirm with their carrier how that payroll is reported to the bureau.
Where to find your official mod
You can get your official experience modification factor from the state's designated rating organization. In many states that is NCCI, which the Nebraska Department of Insurance lists with the number 1-800-NCCI-123. Your agent or carrier can usually pull it for you as well.
Not every state works this way:
- California uses the WCIRB.
- Washington is run through the state's L&I, which calculates a factor for each business annually.
- Other states have independent bureaus, such as the NCRB in North Carolina, which publishes its own calculator and instructions.
If you operate in more than one state, you may have to deal with more than one system. Ask which bureau applies in each state before you request a worksheet.
Calculators are for planning only
Bureau calculators and estimators are useful for what-if scenarios, such as testing how a claim closing would change your number. But WCIRB is clear that its estimators do not produce the official mod used to bind policies. That comes from the authorized rating organization using audited payroll and claim data.
Why your mod might be wrong
Mods are produced from data, and data has errors. When you get your worksheet, check these first:
- Class codes. If payroll sits in a more expensive or more hazardous class than the work performed, expected losses and premiums both shift.
- Claim details. Look for claims that don't belong to you, duplicates, or claims still open with reserves higher than the likely cost.
- Payroll figures. They should match your audits, not estimates.
- Ownership changes. When a business changes hands, the new owner generally inherits its past experience. NCCI says employers should notify their insurer in writing within 90 days using the ERM-14 form or equivalent documentation, so the mod is correctly updated or transferred.
If something looks off, raise it with your agent and the bureau promptly. Corrections are far easier before a policy is bound than after.
How to bring your mod down
There is no shortcut, but the levers are well understood.
- Prevent injuries. This is the whole purpose of the plan. Fewer claims means a lower ratio in future years.
- Report promptly and manage claims. Early reporting and return-to-work programs can keep claim costs smaller. Your carrier's claims team can advise on this.
- Audit your claims every year. Check reserves on open claims and make sure closed claims show as closed.
- Keep payroll classified correctly. Misclassification works against you both in expected losses and in the manual premium.
- Plan for the long game. A bad year stays in your mod for the whole experience period, then rolls off. Because of ballast, the effect in any single year is cushioned, but so is the recovery.
Be wary of anyone who promises to "fix" a mod for a fee without reviewing the underlying data. Legitimate corrections come from fixing errors in the bureau's data, not from negotiating.
Our perspective: the mod is a conversation, not a verdict
Most business owners meet their EMR once a year, as a line on a renewal quote. We think it deserves more attention than that. A mod above 1.00 is not a judgment on your company. It is a signal, and a useful one when someone walks through it with you.
In the policy reviews we do, we look at the mod worksheet next to the policy itself. We check whether class codes match what your crews actually do, whether the payroll reported is right, and whether old claims are still dragging on the number. Because we compare options across more than 25 A-rated carriers, we can also show you how different carriers handle claims service, since the mod is only part of the cost of workers' comp. We put the findings in plain language so you can decide what to do about them.
Our biggest tip for small employers: do not wait until renewal. Ask for your mod worksheet when it is published, and read it while there is still time to correct it. A wrong class code or a stale reserve costs real money every month it stays in place.
— David
Who feels the mod most
The mod matters for every employer with workers' comp, but its effects are sharpest in some places:
- Contractors. Many project owners and general contractors prescreen subcontractors on their mod, so a high number can cost you work as well as premium. If this is your world, see our page on construction and contractor insurance.
- Transportation and logistics. Claims here can be severe, so one event can move the number. We cover coverage options for trucking and transportation.
- Businesses that have been declined or surcharged. A poor loss history can make coverage harder to place. Our high-risk business insurance page explains how hard-to-place risks are handled.
- Growing small businesses. New hires change payroll and classification. Employers with more staff should also check their other exposures, such as employment practices liability.
Get a second opinion before renewal
We are an independent agency licensed in 17 states, including Illinois, Florida and Washington. Our policy review is free and carries no obligation. We look at your current business coverage, flag gaps, and explain what each line does in plain English. If you want to see how other carriers would price your risk, you can request a business insurance quote or start with the free policy review.
In Washington, workers' compensation for most employers goes through the state fund. Ask us what that means for your overall program.
Frequently asked questions
What is a good experience modification rate?
Anything under 1.00 is better than average for your industry, and 1.00 is the neutral baseline. The average mod is 1.0 by design, since it is built around expected losses for similar businesses. What counts as good also depends on your trade, because many contractors and buyers set their own cutoffs.
How long does a claim affect my mod?
A claim stays in the calculation for the whole experience period, which is generally about three years of data. NCCI notes that the period can range from under 12 months to 45 months depending on the policy and whether the business is new. After that the claim drops out of the formula.
Can I calculate my own mod?
You can estimate it, but you can't publish it. Rating bureaus offer calculators, such as the NCRB calculator, that take payroll, class codes and loss figures. They are for informational use. The official number comes from your rating organization, so ask your agent or carrier for the worksheet.
Is a schedule modification the same thing as an experience mod?
No. The experience mod is a standardized, data-driven factor based on your loss history. Schedule rating is a discretionary adjustment by the carrier, and some states restrict or prohibit it. Ask your agent whether it is allowed in your state and whether it applies to your policy.
What happens to my mod if I buy or sell a business?
The new owner generally inherits the business's past experience. NCCI says to notify your insurer in writing within 90 days of an ownership change so the mod can be updated or transferred correctly. Talk to your agent before the deal closes, not after.
Sources
- NCCI: ABCs of Experience Rating
- WCIRB California: Experience Modification
- Washington L&I: Experience Rating
- Nebraska Department of Insurance: Workers' Compensation FAQ
- NCRB: Experience Modification Calculator Instructions
- NCRB: Experience Modification Calculator