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Experience Modifier

A factor calculated from an insured's own loss history that adjusts workers compensation premium up or down from the manual rate — commonly called the e-mod.

businessPublished 2026/06/07Last verified 2026/06/07

FAQs

How long does it take for a loss to stop affecting the experience modifier?
NCCI uses the three policy years preceding the most recent completed year in the modifier calculation. A claim from five years ago no longer appears in the calculation. A claim from the current policy year does not appear until the year after next. This means insureds often see the full impact of a bad claims year two years after it occurred, and the modifier improves approximately four years after the claim date, when it rolls off the calculation window entirely.
Can a single large claim destroy an otherwise favorable experience modifier?
The split point design specifically limits the impact of a single large claim. Only the primary portion (up to the split point threshold) counts at full credibility; the excess is blended with expected excess. A single $500,000 claim will affect the modifier, but it will not have the same impact as $500,000 distributed across many smaller claims, because the excess is partially credibility-weighted. This is by design — actuaries recognize that one large claim may be bad luck rather than evidence of systemic poor safety.
What is the difference between an experience modifier and a schedule modifier?
The experience modifier is calculated objectively by NCCI or the applicable rating bureau using statistical loss data — it is not discretionary. The schedule modifier is applied at underwriter discretion based on qualitative risk factors within the limits of the carrier's filed scheduled rating plan. The two are applied sequentially: experience modification first, then scheduled rating. Both adjustments appear on the policy, and their combined effect determines the final premium.

Related Terms

  • Scheduled Rating

    Manual credits or debits applied by an underwriter to a base premium to reflect risk characteristics not captured by the standard rating algorithm.

  • Split Rating

    Application of different rates to separate portions of a single exposure — for example, different payroll classes within a workers compensation policy.

  • Loss Cost

    The expected claim cost per unit of exposure, excluding carrier expense and profit loadings — the foundation of property-casualty premium calculation.

  • Rating Bureau

    An organization such as ISO, NCCI, or AAIS that collects industry loss data and develops advisory loss costs and policy forms used by member insurers.

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The experience modifier (commonly called the e-mod or experience modification factor) is a multiplicative adjustment applied to a workers compensation manual premium, derived from the individual insured's own loss experience over the prior three policy years (excluding the most recent year). An e-mod of 1.00 means the insured's experience matches the expected average for businesses of similar size and type; a modifier below 1.00 reflects favorable experience and reduces premium; a modifier above 1.00 reflects adverse experience and increases premium.

How It Works / Why It Matters

NCCI administers the experience rating system in most states. The calculation uses actual loss data from the three prior policy years, split into a primary loss component and an excess loss component. This split point design reflects the actuarial principle that high-frequency, lower-severity claims are more predictive of future loss than infrequent catastrophic claims, which may reflect chance rather than underlying risk quality.

The primary loss is the actual incurred amount of each claim up to a threshold (the split point, which varies by state but is typically around $17,000-$22,000). Primary losses receive full credibility — they directly affect the modifier.

The excess loss is the portion of each claim above the split point. Excess losses receive limited credibility — they are averaged with expected excess losses to reduce the volatility impact of a single large claim on the modifier calculation.

Expected losses are calculated by applying the applicable expected loss rates (published by NCCI for each class code) to the insured's payroll. The ratio of actual losses to expected losses — adjusted by the credibility weighting — produces the modification factor.

An insured with zero claims over three years will approach the minimum possible modifier for their size (called the "minimum modification factor"), which is not zero — even a claim-free insured has some expected loss built into the calculation to prevent extreme credits. Large insureds with high premium bases receive more credibility, meaning their actual experience has a greater impact on the modifier than it would for smaller insureds.

In Practice

The e-mod is one of the most consequential numbers in commercial insurance. A mid-size contractor with a manual WC premium of $200,000 and a 1.30 modifier pays $260,000 — $60,000 more than the class average. The same contractor with a 0.75 modifier pays $150,000 — $50,000 less. The modifier directly affects bid competitiveness: contractors must include WC premium in their overhead, and a high modifier raises costs in markets where competitors have lower modifiers.

NCCI issues experience modification worksheets annually, typically 60-90 days before the policy renewal date. Agents and insureds should review these worksheets carefully. Errors in the underlying data — wrong class codes, duplicate entries, open claims with inflated reserves — can produce artificially high modifiers. NCCI has a formal dispute and correction process. Correcting a data error that has inflated the modifier produces an immediate premium reduction on the renewal policy.

Loss control investment has a direct and quantifiable return through the modifier. An insured who implements a formal safety program and reduces frequency of smaller claims will see the primary loss component of their modifier improve over time — typically with a 2-3 year lag reflecting the NCCI calculation window. Agents who can demonstrate this linkage in dollar terms provide concrete value to commercial accounts.

Scheduled rating and the experience modifier interact on WC policies. After the modifier is applied to the manual premium, a separate scheduled credit or debit may be applied to the experience-rated premium. The combination of a favorable e-mod and a scheduled credit can produce total premium well below the manual rate — a strong selling point for carriers who can offer both.

Related Concepts

Split rating determines the manual premium baseline to which the e-mod is applied: accurate payroll allocation by class code is a prerequisite for a correctly calculated experience modifier. If payroll is misallocated — high-hazard employees classified as lower-hazard — the expected losses used in the modifier calculation will be understated, and the modifier may appear artificially favorable.