Updated October 1, 2026.
Commercial lines underwriting prices accounts from loss history, COPE and exposure detail, and the carrier’s portfolio strategy—not from a single automated score. Strong submissions with verified loss runs, complete location data, and credible experience or schedule rating support better terms; thin files get conservative assumptions and weaker pricing.
Commercial underwriting differs from property insurance underwriting on personal lines: mid-size and large accounts are relationship-driven, and judgment calls matter. Market phase matters too—see hard market vs soft market dynamics for how capacity and rate pressure show up in submissions.
Loss run analysis
Loss runs are the primary historical record. Analysis blends dollars (paid, reserved, incurred) with story (cause, repeatability, corrective action).
Definition — Loss development
The process by which a claim’s total incurred changes as payments are made and reserves move. Immature claims show low paid and higher reserves; mature claims show the opposite. Underwriters watch development on open claims—if reserves keep rising, prior carriers may have been optimistic and the account may be worse than the snapshot suggests.
Frequency. Claim count over the experience period signals habits: maintenance, training, supervision. Five small losses often read worse than one large loss with the same incurred, because frequency implies a pattern. High-frequency accounts need a concrete description of fixes, not a generic safety pledge.
Severity. Large losses and open reserves deserve development factors by claim type and age. An open bodily injury or complex property claim with a thin reserve can blow past the incurred shown on the run.
COPE data submission standards
Incomplete COPE (Construction, Occupancy, Protection, Exposure) pushes underwriters to price to worst-case assumptions. Per location, carriers expect address and geocode where needed, TIV split (building, business personal property, business income), year built, construction class, occupancy, stories, square footage, protection class, sprinkler design and percentage of area covered, alarm and monitoring, hydrant distance, and FEMA flood zone for nat-cat screening.
Multi-location accounts submit a TIV schedule with those fields. Catastrophe-exposed portfolios need coordinates accurate enough for portfolio cat modeling—carriers aligning with updated peril views described in climate risk pricing and catastrophe model updates will not quote blind on aggregate PML. Broker-side risk scoring and underwriting data quality should match what the carrier will verify on inspection.
Experience rating and manual pricing
Smaller commercial accounts sit at manual rates plus schedule rating when filed plans allow. Manual rates come from state filings applied to the exposure base (per $100 of value on property, per $1,000 of payroll on workers’ compensation, per $1,000 of revenue on general liability, and so on).
Mid-size and large accounts move into experience rating: actual losses in the experience window are compared to expected losses for the class, with credibility growing as premium volume grows. Favorable history earns credit; adverse history earns debit. Property experience mods are often calculated in the underwriting file from loss runs; workers’ compensation uses published experience modification where NCCI applies.
Schedule rating sits alongside experience rating—premises care, safety programs, and management cooperation can shift manual premium within filed caps even when loss runs are clean.
Large account pricing, reinsurance, and alternatives
Large commercial accounts with stable loss history can access retros, large deductibles, and captives so good loss control shows up in their own economics, not only in the carrier’s margin. Retros tie final premium to incurred losses within min/max bands. Large deductibles ($100,000–$500,000 per occurrence is common on eligible programs) trade premium for retained frequency layer; collateral backs the deductible reimbursement obligation.
Captives fit organizations with enough premium volume (often multi-million-dollar programs) and predictable experience that retaining underwriting profit internally makes sense. Formation involves domicile selection, capital, actuarial support, and tax and regulatory compliance for risk shifting.
Carrier capacity for catastrophe-heavy property still depends on reinsurance and ILS markets. Catastrophe bond issuance reached roughly $18 billion across 83 transactions in the first half of 2026, per Artemis—record half-year activity that supports some property capacity but does not remove strict cat underwriting on individual schedules. How that capacity reaches policyholders is covered in reinsurance fundamentals.
Property values on the submission should align with how the policy will pay—see agreed value vs ACV and RCV when setting building limits.
Frequently Asked Questions
What is a loss run and what information does it contain?
A loss run is a formal report from a current or prior carrier listing all claims on a policy for a specified period—typically five years in commercial property and casualty underwriting. Each line shows date of loss, date reported, cause or claim type, description, paid indemnity, reserve, total incurred, and open or closed status. Carriers require loss runs from every prior insurer for the requested period before quoting. Open claims with large reserves get closer review than closed claims, because reserves are estimates and can develop upward.
What is experience rating and how is it calculated for commercial accounts?
Experience rating adjusts manual premium using the account’s own loss history compared to expected losses for its class, weighted by credibility that rises with account size. The modification compares actual losses in the experience period (commonly three policy years, often excluding the most recent year for development) to expected losses, then blends toward 1.0 when credibility is partial. A mod below 1.0 credits premium; above 1.0 surcharges. Workers’ compensation experience mods are published through NCCI where applicable; on commercial property and other lines the carrier or filing actuary applies the plan filed in that state.
What is schedule rating and how does it differ from experience rating?
Schedule rating changes manual premium based on current, observable risk characteristics—premises condition, training, management cooperation, location, and similar factors—not based on paid claims history. Experience rating reacts to what already happened on the loss runs. Schedule credits and debits are capped by state-filed plans (often near ±25% per factor and ±40% total) and require documented underwriter rationale so they are not applied arbitrarily.
What is a retrospective rating plan and which commercial accounts benefit from it?
A retrospective rating plan sets final premium after the policy period using actual incurred losses, subject to contractual minimum and maximum premiums. Larger accounts—often well above $100,000 in standard premium—use retros when they want premium to track loss control results and can absorb year-to-year variance. Small accounts usually lack credibility for retro mechanics; volatility would dominate the adjustment.
What makes a commercial submission strong enough to attract competitive underwriting?
Competitive underwriting starts with complete COPE and exposure data, five years of carrier-issued loss runs, and a clear narrative on safety culture and fixes after prior claims. Catastrophe-exposed schedules need geocoded locations so carriers can run cat models; valuation should reflect current replacement cost or agreed value where appropriate. In a firm market, clean documentation and broker analysis still win attention from underwriters managing tight capacity.