Loss Run

What Is a Loss Run?

A loss run is a document produced by an insurance carrier that details the claims history associated with a specific policy or insured entity over a defined period. It lists each reported claim, including date of loss, type of claim, amounts paid (indemnity and expense), amounts reserved for future payments, and claim status (open or closed). Loss runs are the primary evidence underwriters use to evaluate an applicant's historical risk performance.

In commercial property and casualty insurance, loss runs function as the financial transcript of a risk. Just as a credit report summarizes borrowing behavior, a loss run summarizes claims behavior. Underwriters rely on loss runs to answer a fundamental question: does this applicant's actual claims experience justify the premium being charged?

Loss runs are typically requested for the most recent three to five policy years, though carriers writing large or complex accounts may request seven or more years. They are produced by the incumbent carrier or carriers and delivered to the broker, who includes them in the submission package sent to prospective underwriters.

What a Loss Run Contains

A standard loss run includes several data elements per claim. The specifics vary by carrier format, but the core fields are consistent across the industry.

Policy information: policy number, effective dates, named insured, line of business, and sometimes the producing agent or broker.

Claim-level data: claim number, date of loss, date reported, claimant name (in liability lines), claim type or cause of loss, and jurisdiction or state.

Financial fields: paid indemnity (the amount paid to or on behalf of the claimant), paid expense (allocated loss adjustment expense, or ALAE), case reserves (amounts set aside for anticipated future payments on open claims), and total incurred (paid plus reserves). Some carriers also break out subrogation recoveries and deductible reimbursements.

Claim status: whether the claim is open (still being adjusted), closed (fully resolved), or reopened.

Valuation date: the date through which the financial data is current. This matters because reserves change as claims develop. A loss run valued six months ago may not reflect recent reserve increases or settlements.

The challenge for underwriting teams is that no two carriers format loss runs identically. One carrier produces a clean PDF table. Another delivers a multi-page text file with inconsistent column alignment. A third embeds loss data in a spreadsheet with merged cells and footnotes. This format variation is the root cause of the extraction problem that slows commercial underwriting workflows.

Why Loss Runs Matter for Underwriting Decisions

Loss runs serve four critical functions in the underwriting process, each directly tied to pricing accuracy and portfolio profitability.

Risk selection: Loss history is the strongest predictor of future claims performance for most commercial lines. An applicant with three years of clean loss runs in workers' compensation presents a fundamentally different risk than one with multiple open indemnity claims and rising reserves. Underwriters use loss frequency (how many claims) and loss severity (how large each claim) to determine whether a risk fits within appetite.

Pricing validation: Actuarial pricing models incorporate expected loss ratios by class code and territory. Loss runs provide the actual experience that either confirms or contradicts those expectations. When actual losses significantly exceed expected losses, the underwriter must either increase rate, add exclusions, or decline the risk. When losses run favorable, the underwriter has room to compete on price while maintaining margin.

Experience rating: In workers' compensation, loss run data feeds directly into the experience modification rate (EMR) calculation. The EMR adjusts premium based on the employer's claims history relative to industry averages. Accurate loss data is therefore inseparable from accurate premium calculation.

Renewal evaluation: At renewal, underwriters compare current-year losses against prior-year performance. Deteriorating loss trends signal potential pricing inadequacy. Improving trends may support retention pricing. Without accurate, current loss runs, renewal decisions rely on incomplete information.

The Loss Run Extraction Problem

For most commercial carriers and MGAs, loss run processing remains one of the most labor-intensive steps in the submission workflow. The challenge is structural, not a matter of effort or skill.

A mid-market carrier processing 200 submissions per week receives loss runs from dozens of different incumbent carriers. Each carrier uses a proprietary format. Some deliver PDFs generated from mainframe systems with fixed-width text layouts. Others produce Excel exports with inconsistent column headers. Still others provide scanned images of printed reports, requiring OCR before any data extraction begins.

Manual processing of a single multi-year, multi-line loss run takes 30 to 60 minutes for an experienced underwriting assistant. At scale, this creates a bottleneck that directly affects quote turnaround time. When a broker submits to five carriers simultaneously, the carrier that returns a quote first wins the business more often than not. Speed matters, but only when paired with accuracy.

Template-dependent automation tools break when formats change. A carrier that redesigns its loss run layout, or a broker who submits loss data in an unexpected format, forces the system back to manual processing. This is why many carriers that invested in first-generation OCR solutions found adoption stalled: the tools worked on 60 to 70% of documents but required manual intervention on the rest, creating a workflow that was more complex than pure manual processing.

Template-agnostic extraction technology addresses this by parsing loss run data regardless of carrier format, without requiring pre-built templates for each layout. The system identifies the semantic structure of the document (claim number, date, paid amounts, reserves) rather than relying on fixed positions on the page. For carriers handling hundreds of formats across their submission flow, this distinction determines whether automation delivers consistent value or intermittent frustration.

Loss Runs and Data Accuracy

Inaccuracy in loss run extraction compounds across the underwriting workflow. A transcription error in paid losses changes the loss ratio calculation. A missed open claim understates reserve exposure. An incorrect valuation date means the underwriter is pricing against stale data.

Consider a commercial auto fleet account with a $2 million book. If loss run extraction misreads total incurred losses by $50,000, that error shifts the loss ratio by 2.5 percentage points. Across a portfolio of 500 accounts, even a 1% systematic error rate in loss data extraction creates measurable adverse selection: the carrier systematically underprices risks with worse-than-reported losses and overprices risks with better-than-reported losses.

This is why the 2026 market emphasis on data quality as an underwriting differentiator has direct implications for loss run processing. As carriers compete on speed and accuracy in a softening property market, the quality of the data driving risk selection determines who writes profitable business and who accumulates adverse selection.

Verified accuracy in loss run extraction, where every extracted data point links back to its source document with full provenance, eliminates the trust gap that causes underwriters to re-check automated output manually. When the system shows its work, underwriters act on the data rather than verifying it, which is the difference between automation that saves time and automation that creates additional steps.

Loss Runs by Line of Business

Loss run complexity and importance vary across commercial lines.

Workers' compensation: Loss runs are critical because they feed EMR calculations and reflect frequency-severity patterns that define employer risk. WC loss runs typically include detailed claim type breakdowns (medical only vs. lost time vs. permanent disability) and may span multiple states with different regulatory requirements.

Commercial auto: Loss runs for fleet accounts often include vehicle-level detail, driver information, and jurisdiction-specific claim data. Given that commercial auto combined ratios have exceeded 103% in 12 of the past 14 years, accurate loss run analysis is essential for identifying deteriorating trends before they reach the renewal.

General liability and commercial property: GL loss runs distinguish between premises, products, and completed operations claims. Property loss runs detail cause of loss (fire, wind, water, theft) and may include catastrophe-coded events. Both require careful parsing to separate attritional losses from large or catastrophe losses in experience rating.

Professional liability: Claims-made loss runs require attention to reporting dates and policy periods. An incorrectly mapped claim date can place a loss in the wrong policy year, distorting both the current and prior loss ratios.

How Long Should Underwriters Request Loss Runs?

Industry standard is five years for most commercial lines. However, the appropriate period depends on the risk profile. Workers' compensation and commercial auto accounts benefit from five to seven years because frequency patterns emerge over longer windows. Professional liability, where claims develop slowly, may require seven to ten years for a complete picture. Short-tail property risks may be adequately assessed with three years.

The valuation date matters as much as the period length. A five-year loss run valued six months ago may miss significant reserve movements on open claims. Best practice is to request loss runs valued within 90 days of the quote date, particularly for casualty lines where reserve development is common.

Key Takeaway

Loss runs are the evidentiary foundation of commercial underwriting. Every pricing decision, every renewal evaluation, and every portfolio management action depends on the accuracy and completeness of loss data. In a 2026 market where technical underwriting precision separates profitable carriers from those accumulating adverse selection, the speed and reliability of loss run processing directly affects competitive positioning. Carriers that extract loss data accurately, consistently, and at speed turn submission volume into underwriting advantage rather than operational overhead.