Workers’ Compensation Experience Modification Factor

Two employers can have similar payroll and job classifications but different workers’ compensation premiums because their loss histories differ. An experience modification factor (also called an experience rating modification or e-mod) is one rating adjustment that reflects an employer’s past loss experience under a prescribed plan. It is not a grade for workplace safety, a guarantee of future claims, or the full formula for the final premium.

In Texas, workers’ compensation rates can include classification loss costs or an insurer’s own filed rating basis, and insurers may apply other factors such as schedule rating, deductibles, premium credits, and minimum premiums. TDI’s current rate guide explains that an experience modifier reflecting the employer’s past loss history may be applied. The final bill can therefore differ from a simple class rate multiplied by payroll.

What the experience mod measures

Experience rating compares an employer’s actual reported losses and exposures with expected losses for the employer’s classifications, payroll, and rating period. It is intended to make premium more responsive to an individual employer’s loss history while maintaining a common rating framework. The mod is a factor applied to a defined premium component; it does not literally mean that the employer is a certain percent safer or riskier than every other business.

A factor of 1.00 is often called unity. A factor below 1.00 generally reduces the portion of premium to which the factor applies, while a factor above 1.00 generally increases it. For a simplified illustration, if the experience-rated premium component is $40,000 and the mod is 0.90, applying that factor would yield $36,000 before other rating adjustments. If the mod were 1.15, the corresponding component would be $46,000. Actual Texas premium calculations include other elements and can use a different order or base.

The experience mod is not a dollar credit or a discount guarantee. It does not necessarily apply to every premium component, and an insurer may have filed rules for other adjustments. A company with a favorable mod can still pay more because payroll, class mix, rates, coverage limits, assessments, schedule factors, or minimum premium changed. A business with a surcharge may still improve its mod as its experience period changes and its loss data develops.

What goes into experience rating

Rating data generally includes payroll by classification and reported claim losses during a defined experience period. The rating plan distinguishes losses that are more predictable from losses that are less predictable and may limit or weight losses in a prescribed way. The precise split points, weights, eligibility rules, and calculation method change under the adopted manual and rating plan. TDI has adopted NCCI experience-rating materials with Texas exceptions; do not rely on an outdated formula or a generic national example as a current Texas calculation.

Claim frequency and claim severity both matter. Several smaller claims can affect the rating calculation differently from one large claim, depending on plan rules. Certain medical-only losses may receive a specific adjustment under the Texas plan. The modification does not simply sum every claim dollar and divide it by payroll. Rating plans use credibility concepts and other factors to avoid treating a small employer’s limited history as a perfect predictor of its future losses.

Payroll is important because it provides an exposure base and affects expected losses by classification. Misclassification can distort both the premium and experience rating. Employees who perform different kinds of work may need payroll allocated according to classification rules and reliable records. Owners, officers, clerical staff, subcontractors, and temporary workers can be handled under specific rules; the insurer or rating organization should not be given unsupported estimates.

The rating period does not necessarily use the most recent policy year. A claim reported today may not affect the current factor immediately, and a claim can develop after the policy has expired. Conversely, data errors or late corrections can change a modification. The employer should examine the effective date, experience period, policy years included, payroll reports, claim records, and any revised worksheet when a factor appears unexpected.

How a claim can affect the factor

A work injury first affects claim handling and benefits; its rating effect is a separate question. The insurer may pay medical and income benefits under the policy and Texas law. The experience rating plan later applies its own treatment to the loss. Employers should not discourage injured workers from reporting claims or delay medical attention to protect a premium factor. Prompt reporting and safe return-to-work practices protect people and can support sound claim management.

Not every dollar of a large claim necessarily affects the factor in the same way. Plans can cap or weight losses, account for medical-only claims, or apply a split between primary and excess losses. The purpose is to prevent one severe event from overwhelming the rating result while preserving some influence of actual experience. The details are found in the rating plan manual and any state exceptions, not in the shorthand phrase ‘claims raise the mod.’

A disputed claim is not automatically excluded from experience data. The insured should work with the carrier and agent to correct inaccurate information, identify duplicate or misallocated claims, and understand how claim status and loss amounts are reported. The rating organization’s records and policy data need to be accurate. A reserve is an estimate used in claim handling; the mod’s calculation follows plan rules and may include loss information not equal to the check payments made so far.

How the factor interacts with premium

A simplified premium sequence begins with payroll divided by a rating unit and multiplied by the rate or loss cost for each classification. The insurer’s filed loss-cost multiplier or other filed rating basis may then apply, followed by experience modification, schedule rating, deductible credit, premium discount, expense constant, catastrophe or terrorism elements, and minimum premium rules as applicable. The exact order and components are policy- and filing-specific. TDI’s rate guide provides current rate-basis information and a sample calculation.

A worked example

Assume an employer has $1,000,000 of payroll in a single classification and a filed rate basis of $2.00 per $100 of payroll. The simplified manual premium is $20,000. If an experience factor of 1.10 applies to that component, the simplified experience-rated amount becomes $22,000. A separate schedule credit, deductible credit, premium discount, expense constant, or minimum premium may then change the invoice. This example is for understanding the factor only and is not a Texas quote.

Now suppose the payroll estimate was too low and the final audit finds $1,200,000 of covered payroll. The exposure basis increases even if the factor stays at 1.10. If the employer also had a class-code change or the insurer updated its filed rates, the premium may move for multiple reasons. To understand the bill, separate changes in payroll, classifications, base rates, experience modifier, schedule rating, and other line items instead of attributing the entire increase to claims.

Who calculates and issues the modification?

TDI adopts the relevant experience-rating framework with Texas exceptions, and NCCI administers rating plans and data processes for participating jurisdictions. The insurer applies the proper factor under the applicable policy and filed rating basis. Eligibility thresholds and calculation rules can change, so an employer should use its current experience-rating worksheet or carrier explanation rather than a historical article that quotes a dollar or payroll threshold.

The employer’s agent can help reconcile payroll, class codes, claims, and the experience worksheet, but should not guess at an unexplained factor. Ask which policy years were included, whether the modification is final or revised, what loss data was used, whether medical-only adjustments applied, and which premium components the factor modified. If the employer identifies an error, provide supporting records promptly and ask the carrier or rating organization how a correction is requested.

Ways to improve future experience

The factor is retrospective in the sense that it reflects prior experience, so a safety initiative does not instantly change an existing factor. Risk control can improve future outcomes by preventing injuries and limiting claim severity. Review incident patterns, job hazards, equipment, training, housekeeping, lifting, vehicle use, fall protection, and return-to-work processes. In Texas, DWC offers workplace safety resources and TDI’s OSHCON program provides consultations to employers.

Investigate injuries early, document what happened, provide appropriate medical care, and keep communication open with the injured employee and claims administrator. Modified work can help some employees return safely if it is medically appropriate and coordinated with the treating provider. The employer should not interfere with medical treatment or pressure a worker to avoid a legitimate claim. Accurate payroll, prompt reporting, and correcting classification errors are also practical ways to keep the rating data reliable.

Audit your experience worksheet at each renewal. Compare reported losses with the carrier’s loss runs, verify that claim amounts and classifications belong to the correct entity, and flag claims that appear duplicated or associated with another policy. Keep records for subcontractor certificates, payroll, job descriptions, and ownership changes. If the employer changes business operations, update the carrier so the classification and exposure information remain accurate.

Common mistakes

• Treating 1.00 as a promise of a particular final premium rather than a unity experience factor.
• Assuming every paid dollar from every claim affects the e-mod dollar for dollar.
• Assuming a claim changes the factor in the same policy year it occurs.
• Confusing the experience modifier with schedule rating, loss costs, or the payroll audit.
• Using an outdated national formula or an expired Texas manual instead of current adopted rules.
• Misclassifying payroll or failing to keep employee and subcontractor records.
• Discouraging injury reporting or medical care to try to influence a future premium factor.
• Assuming a favorable e-mod means that the employer has adequate coverage or has no safety problems.

Exam takeaway

The experience modification factor compares an employer’s past loss experience with expected losses under the applicable workers’ compensation rating plan. A unity factor of 1.00 is the benchmark; a lower factor can reduce and a higher factor can increase the premium component to which it applies. Classification, payroll, loss data, rating eligibility, and plan rules matter. The mod is one premium factor, not the full calculation, a safety score, or a guarantee of future claims.

When a factor changes sharply, begin with a reconciliation rather than assuming the rating plan made a mistake. Compare the current worksheet with the prior one: experience period, payroll by class, claim identifiers, incurred loss amounts, any split or adjustment, and the effective factor date. Ask the carrier which reports were used and whether a claim reopened, reserve changed, or payroll was corrected. The experience modification is based on reported inputs and plan calculations, so an error in an upstream record can propagate into the factor. Maintain dated copies of the worksheet and correction requests so the next renewal review can track whether the issue was resolved. Employers should also keep the mod in context. It can be useful when comparing premium changes or discussing safety trends, but it cannot measure every hazard or predict a particular worker’s claim. A single low-frequency, high-severity exposure may remain important even when past experience is favorable. Likewise, a factor that is higher than unity does not establish that the employer has violated a safety rule. Use the factor as one signal alongside incident data, worksite inspections, and the carrier’s underwriting review.

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