What Is an Experience Modification Rate (EMR)? How the Mod Is Calculated and Read

8/20/2026

The experience modification rate (EMR, experience mod, or simply "the mod") is the one number in a workers' compensation premium that belongs to you. The class code rate is shared by every employer doing the same kind of work. The payroll is whatever your business needed to run. The mod is your own claims history, measured against what was expected of an employer your size in your classifications, and turned into a multiplier.

That multiplier lands on the whole premium. A 1.25 mod means paying 25% more than the manual premium; a 0.80 mod means paying 20% less. On a construction bid it can also decide whether you are allowed to bid at all. This guide explains what the number means, how it is built, why it reacts to claims years after they happen, and how to read the worksheet that produces it.

What the Mod Actually Measures

Workers' comp rates are set per classification. Every employer in a class code pays the same rate per $100 of payroll, which is an average built from the losses of all employers in that class. Some of those employers are safer than average and some are not. Experience rating is the adjustment for that difference.

In NCCI's own description, the experience rating plan compares the experience of an individual employer with the average employer in the same classification, and the difference is reflected in a modification factor based on that employer's payroll and loss records. The result can increase premium, decrease it, or leave it unchanged.

Three outcomes are possible:

• 00 (unity). Your experience is in line with what was expected, or you are not experience rated at all. NCCI assigns a unity mod when an employer does not meet the eligibility requirements, lacks the minimum data, is a new business with no history, or has an ownership change that prevents the data from being used, as well as when the calculation genuinely produces 1.00.
• Below 1.00 (a credit mod). Your actual losses were lower than expected. Premium goes down by the same proportion.
• Above 1.00 (a debit mod). Your actual losses were higher than expected. Premium goes up.

The mod is a ratio, not a grade. A 1.00 is not "average safety" in any moral sense; it means the formula could not distinguish your experience from the expected losses for your payroll and classes. Two employers with identical injury counts can carry different mods because they are different sizes, operate in different classes, or had claims of different shapes.

Who Calculates It

Who produces your mod depends on where your employees work, and this is the first point where generic advice goes wrong.

NCCI states. NCCI calculates mods under its Experience Rating Plan Manual. According to NCCI's ABCs of Experience Rating, 39 jurisdictions have approved the plan. Indiana, Massachusetts and North Carolina use the plan, but their own rating organizations produce intrastate mods. Minnesota and Wisconsin have independent rating organizations that allow their experience to be combined into an NCCI interstate mod when the employer also has exposure in other participating states.

Independent bureau states. NCCI's plan does not apply in California, Delaware, Michigan, New Jersey, New York or Pennsylvania. Each has its own rating bureau and its own experience rating rules. California's Workers' Compensation Insurance Rating Bureau (WCIRB), for example, calculates what it calls the X-Mod under the California Workers' Compensation Experience Rating Plan, using expected loss rates, D-ratios and primary thresholds that vary with employer size.

Monopolistic states. North Dakota, Ohio, Washington and Wyoming run their own state funds with their own rating plans. Washington, for instance, bases most premiums on hours worked rather than payroll and caps year-over-year experience factor changes, according to the Department of Labor and Industries.

If you have employees in several NCCI states, you will usually receive a single interstate mod. If you also have employees in Pennsylvania or California, you will carry a separate intrastate mod there, produced by that state's bureau from that state's data only. Multi-state employers frequently have two or three mods in force at the same time, and a contractor answering a prequalification form needs to know which one the owner is asking for.

The rest of this article describes the NCCI method in detail because it covers the most states and NCCI publishes it openly. The concepts (expected losses, primary and excess, weighting, ballast) are similar in the bureau states, but the parameters and some of the mechanics are different. If your mod comes from WCIRB, PCRB, NYCIRB or another bureau, read that bureau's published plan before relying on any number here.

Why the Mod Is Always Looking Backward

The most misunderstood feature of the mod is timing. Your current mod does not include your current policy year, and it does not include the year before that either.

NCCI's published example: for a mod with a rating effective date of January 1, 2026, the experience period generally includes policies effective January 1, 2022, January 1, 2023 and January 1, 2024. The 2025 policy is excluded because its losses have not yet been valued and reported. Technically, a policy is used if its effective date falls no less than 21 months and no more than 57 months before the rating effective date. Carriers are not required to report a policy's data until 18 months after inception, and the mod itself is usually calculated 60 to 90 days before it takes effect.

So the experience period is generally three years, but NCCI notes it can range from less than 12 months of data to as much as 45 months, depending on short policies, changes in effective date or a new employer qualifying from its first policy.

The practical consequences:

• A bad year hurts for three years, starting roughly two years after it happens. An injury in mid-2024 will typically appear in the mods effective in 2026, 2027 and 2028.
• A safety improvement takes years to show. The program you launch this quarter will not touch your mod until its first full year of data rolls into the experience period.
• The oldest year drops off each renewal. If your mod is high because of one bad year, you can predict when relief arrives by finding that year on the worksheet.
• Claims are valued as of a point in time. Reserves set on open claims count as losses. An open claim carrying a large reserve inflates the mod until it is reduced or closed, which is why reviewing reserves with your carrier before the valuation date matters.

Frequency vs. Severity: Why Small Claims Cost More Than You Think

The second thing the formula does that surprises employers is treat the number of claims as more telling than their size.

NCCI's reasoning is statistical. Whether an accident happened is predictable; how much it ends up costing is much more a matter of chance. NCCI's own illustration compares two similar employers in the same class: Employer A with one loss of $50,000 and Employer B with ten losses totaling $50,000. Employer B, with the higher frequency, is expected to have higher future costs, because any one of those ten accidents could have become the expensive one.

The plan builds that view into the math with a split point:

• The portion of each claim up to the split point is primary loss, and represents frequency.
• The portion above the split point is excess loss, and represents severity.
• A claim smaller than the split point is all primary.

Primary losses get much heavier weight in the formula than excess losses. In NCCI's ABCs document, which uses an $18,500 split point for its examples, a single $50,000 loss contributes $18,500 of primary loss, while ten $5,000 losses contribute $50,000 of primary loss. Same dollars, very different mod.

The split point has changed considerably. For years it was $5,000. NCCI's 2013 update raised it over a three-year transition (to $10,000, then $13,500, then $15,000 plus inflation) and then indexed it for claim inflation. NCCI's more recent methodology update, effective with state rate filings from November 1, 2023 (most commonly January 1, 2024), moved from a single countrywide split point to state-specific split points, and also recalculated the state per-claim accident limitations and the weighting and ballast values. If you compare a worksheet from 2015 with one from 2026, the numbers are not built the same way. The current split point for your state appears on your worksheet's summary page.

Two further limits keep single large claims from dominating:

• State per-claim accident limitation. Each loss is capped at a state-specific amount for rating purposes. Anything above it is non-ratable and does not enter the mod.
• Experience Rating Adjustment (ERA). In states that have approved it, which NCCI describes as most of them, medical-only claims enter the mod at 30% of their value. NCCI introduced this to remove the incentive for employers to pay small medical claims out of pocket instead of reporting them.

That last point deserves emphasis. Paying claims "off the books" to protect the mod is a poor trade in an ERA state, it may violate your policy's duty to report injuries, and it can collide with state claim-reporting requirements. Report every injury to the carrier.

How the Mod Is Calculated (NCCI Method)

You do not need to calculate your own mod, but you do need to understand the parts well enough to check one. The NCCI worksheet works in four steps.

Step 1: Expected losses

For each class code on each policy in the experience period, the worksheet multiplies the expected loss rate (ELR) by payroll divided by 100. The ELR is the expected loss for that class per $100 of payroll. Then it multiplies expected losses by the D-ratio (discount ratio), which is the share of expected losses that are expected to be primary. That gives expected primary losses. Expected excess losses are the difference between the two.

This step is why payroll and classification errors flow straight into the mod. Payroll reported in the wrong class carries the wrong ELR, which changes the expected losses your actual losses are measured against.

Step 2: Actual losses

Each claim is listed with its incurred amount (paid plus reserves), combining indemnity and medical. Claims are limited by the state accident limitation, medical-only claims are reduced under ERA where it applies, and each claim is split into primary and excess. NCCI's worksheet lists claims over $2,000 individually and may group smaller claims by injury type.

Step 3: Weighting and ballast

Two stabilizers keep the result from swinging too far:

• W (weight) is the weight given to excess losses. It is small for small employers and grows with size, so a large employer's mod reflects more of its own severity.
• B (ballast) is added to both sides of the fraction. NCCI compares it to ballast in a ship's hold: it keeps the mod from moving too far from 1.00 because of any single loss. Ballast increases as expected losses increase.

The underlying principle, in NCCI's words, is that the larger the employer, the more credible its own record is in predicting its future losses. A small employer's mod moves less in both directions than a large employer's, because a small employer's few claims are a weaker signal.

Step 4: The formula

In summary form, the NCCI mod is:

Mod = (Actual primary + W × Actual excess + (1 - W) × Expected excess + Ballast) ÷ (Expected losses + Ballast)

The numerator is your adjusted actual losses. The denominator is your adjusted expected losses. If they are equal, the mod is 1.00.

Look at what that structure implies. Your actual primary losses enter at full weight. Your actual excess losses enter only at the W weight; the remainder of that slot is filled with expected excess, not your own. For most small and mid-size employers, W is low, so the mod is driven mainly by actual primary losses, which means by claim count. That is the arithmetic behind "frequency matters more than severity."

Reading Your Experience Rating Worksheet

The worksheet is the source document. Ask your agent or carrier for it every year; in NCCI states it is available through NCCI's Riskworkstation to the carrier of record and to agents with a letter of authority, and employers can request their own. California policyholders can request their worksheet from WCIRB.

Check these items in this order:

1. NCCI mods can be preliminary (calculated with the prior approved rating values), final, or contingent (issued while NCCI is still waiting for audited payroll or losses). A preliminary or contingent mod can change.
2. Rating effective date. Confirm it matches your policy renewal. A mismatch often indicates an ownership or date change that needs attention.
3. Experience period policies. Every policy year in the window should be present. A missing year usually means a carrier did not file its unit statistical report.
4. Payroll by class. Compare each year's payroll by class code to your audited payroll. Payroll that was reassigned at audit should appear in the corrected class.
5. Claims list. Look for claims that are not yours, duplicates, claims coded as lost-time that were medical-only, and open claims with reserves that no longer reflect reality.
6. Ownership combination. NCCI combines the experience of entities with more than 50% common majority ownership. Make sure the right entities are combined, and no unrelated ones.

Errors at any of these points flow straight into the mod. Most corrections go through the carrier that reported the data, not the rating bureau, so start there.

A related trap: ownership changes. NCCI requires employers to notify their carrier in writing within 90 days of a change in ownership (on the ERM-14 form or equivalent), and NCCI may revise the current mod and up to two prior mods as a result. Buying a company with a high mod, or restructuring to escape one, is exactly what the ownership rules are designed to catch.

Why General Contractors and Owners Ask for Your EMR

In construction, the mod has a second life as a safety credential. Owners, general contractors and public agencies routinely ask subcontractors for their EMR on prequalification forms, often alongside OSHA injury and illness log figures. Many set a ceiling, and a mod above it can disqualify a bid regardless of price.

That use has real limitations, and the people setting thresholds do not always appreciate them:

• The mod lags. A contractor's current mod reflects claims from roughly two to four years ago, not current performance.
• The mod is size-sensitive. A small contractor with one serious claim can carry a high mod for three years; a large contractor absorbs the same claim with little movement.
• Mods are not comparable across bureaus. A California X-Mod, a Pennsylvania mod and an NCCI interstate mod are produced by different plans.
• Unity is not a safety record. A contractor too small to be experience rated carries a 1.00 by default.

If you are on the asking side, ask for the worksheet or a bureau letter, not a number typed onto a form, and read it alongside the OSHA log. If you are on the answering side, keep your current worksheet and a short explanation of any large or unusual claim ready. A one-page note explaining that a debit mod is driven by a single 2023 claim that falls out of the experience period at the next renewal can keep you on a bid list.

What Actually Lowers a Mod

Because of the lag and the weighting, the actions that move a mod are mostly operational, and mostly slow.

Prevent claims, especially frequent small ones. Primary losses drive the mod. A pattern of minor lost-time injuries costs more mod points than one large claim.

Report every injury promptly. Delay drives claim cost and litigation. The hub-level rule is simple: the claim you report late is the claim that grows.

Return people to work. Lost time drives indemnity, indemnity drives incurred losses, and those losses drive the mod. A transitional-duty program is the highest-leverage tool most employers have. See our return-to-work program guide.

Manage open claims and reserves. Ask the adjuster for a claim review before the valuation date. An overstated reserve on an open claim counts as a loss until it changes.

Get the payroll and class codes right. Expected losses come from payroll by class. Payroll in the wrong class shifts expected losses and therefore the mod. Our guide to calculating workers' comp premiums covers how payroll, rate and mod combine.

Check the worksheet every year. Data errors are the only mod problem you can fix immediately.

Watch for fraud. A claim that should not exist is still a loss in the mod until it is resolved. Our post on workers' comp fraud red flags covers what to look for on both the claimant and the employer side.

Where Payroll Fits

Payroll is involved at both ends of the mod. On the input side, the payroll you report by class at audit becomes the exposure the mod is measured against. On the output side, the mod applies to every dollar of premium for the year, and payroll is often the department asked to explain the renewal increase.

The Workers' Comp Premium Control: Experience Mods, Classifications and Audit Mastery program is built for exactly this intersection of experience mods, classification and audit. For the broader payroll role in workers' comp, start with our Workers' Compensation 101 guide for payroll professionals, the payroll department checklist for workers' comp, and the rules for your state (for example, California or Pennsylvania, both independent bureau states).

Frequently Asked Questions

What is a good experience modification rate?

Anything below 1.00 is a credit mod, meaning your losses were lower than expected for your size and classes and you pay less than manual premium. In practice, "good" is set by whoever is asking. Many owners and general contractors use 1.00 as a prequalification ceiling, and some set it lower. Remember that a 1.00 can also mean you are simply too small to be experience rated, and that a mod reflects claims from roughly two to four years ago rather than current performance. A worksheet that shows the trend is more persuasive than the single number.

How long does a claim affect my EMR?

Under the NCCI plan, a policy year generally sits in the experience period for three consecutive mods. Because the most recent completed year is excluded while its losses are still being valued, a claim usually begins affecting the mod about two years after the policy it occurred in started, then stays for three renewals before dropping off. Independent bureau states use their own experience periods, so check your bureau's plan. Your worksheet lists each policy period it uses, which is the easiest way to see when a specific claim will roll off.

Why did my mod go up when I had fewer claims this year?

Several reasons are common. The year that dropped off may have been a very good one, so losing it raised the average. Open claims from earlier years may have been re-reserved upward. Your payroll may have fallen, lowering expected losses while actual losses stayed the same. Updated state rating values (expected loss rates, D-ratios, split points, weights and ballast) also change each year with the state's rate filing. Finally, the year with fewer claims may not be in the experience period yet. Compare the new worksheet with last year's line by line.

How do I look up an EMR rating?

Employers should request their own worksheet through their insurance agent or carrier. In NCCI states, the carrier of record and agents with a letter of authority can access mods and worksheets in NCCI's Riskworkstation application, and employers can request their own worksheet from NCCI. In California, policyholders can request their experience rating worksheet from WCIRB. Other independent bureau states have their own request processes. If you are checking a subcontractor, ask them for the worksheet or bureau letter rather than relying on a number on a form.

Does paying small claims out of pocket keep my mod down?

In most NCCI states, very little. Under the Experience Rating Adjustment, medical-only claims enter the mod at only 30% of their value, so a small medical-only claim has a modest effect. Paying it privately also risks breaching the policy's requirement to tell the carrier about injuries that may be covered, can conflict with state injury-reporting rules, and leaves you exposed if the "minor" injury turns into a lost-time claim later. Reporting every injury is the safer and usually the cheaper path.

Can a mod be changed after it is issued?

Yes. A mod can be revised when it was issued as preliminary or contingent and the final values or audited data arrive, when a carrier corrects its reported payroll or losses, or when an ownership change requires recalculation. NCCI may revise the current mod and up to two prior mods because of ownership or combination changes. If you find an error on the worksheet, contact the carrier that reported the data first, since the rating organization calculates from what carriers file. Keep documentation of the error and the correction.

Build the Skill In-House

The mod is easy to quote and hard to manage, because the decisions that move it happen years before the number changes. Payroll and HR teams that understand the worksheet catch data errors, push for timely claim reviews and explain renewals with confidence. The Workers' Comp Premium Control: Experience Mods, Classifications and Audit Mastery program covers experience mods alongside the classification and audit work that feeds them. For quick answers to common questions, see our workers' comp FAQs.