Written by Justin Goodman, CIC, CISC, CLCS, CEO and Co-Founder, Total CSR Published: September 30, 2026 · Last reviewed: September 30, 2026
In plain language: Loss runs are reports from an insurance company that list every claim a business has filed, how much each claim cost, and whether it is still open. Underwriters use these reports to decide whether to offer coverage and at what price.
Technical definition: Loss runs are carrier-generated or TPA-generated reports summarizing a policyholder’s claims activity over a specified period, typically three to five years. Each entry shows claim number, date of loss, cause, reserve amount, paid-to-date figures, and open or closed status, feeding directly into underwriting and experience rating.
Loss Runs at a Glance
| Attribute | Detail |
|---|---|
| Also known as | Loss history report, claims experience report, loss summary report |
| Category | Underwriting documentation |
| Lines of business | Commercial General Liability, Commercial Auto, Workers Compensation, Property |
| Industries most affected | Construction, trucking, habitational real estate, manufacturing |
| Who bears the risk | Policyholder, through higher premiums or declined coverage if history is poor or undisclosed |
| Common solution | Request annual loss runs in writing before renewal; review for reserve accuracy |
| Also interacts with | Experience modification factor, applications, renewal underwriting |
Key Takeaways
- Loss runs are claim history reports issued by an insurer or third-party administrator showing a policyholder’s past losses by date, cause, and dollar amount.
- Agencies rely on loss runs to market accounts to new carriers, verify experience modification calculations, and catch reserve errors that inflate future premiums.
- The most common pitfall is accepting loss runs at face value without checking reserve amounts, since inflated reserves on open claims can distort pricing for years.
- A strong practice is requesting loss runs at least 90 days before renewal, giving time to dispute incorrect reserves before a carrier quotes off bad data.
What Is Loss Runs in Insurance?
Loss runs are standardized reports carriers produce to document a policyholder’s claim history, and they exist because underwriters cannot price risk on promises alone. An applicant can describe a safe operation, but a carrier wants documented proof of how claims actually unfolded. Loss runs supply that proof, turning subjective risk perception into a dataset an underwriter can compare across similar accounts.
The reports typically cover three to five years and break out each claim by line of business, date of loss, claimant, cause of loss, incurred amount, paid amount, and reserve. Reserves matter enormously because a claim reported as open with a large reserve can suppress a policyholder’s attractiveness to new markets even if the carrier never pays that amount out. A contractor with a single $250,000 reserve sitting on an otherwise clean five-year loss run may get quoted as if that full amount were already paid, simply because the reserve has not been closed or reduced.
Consider a roofing contractor switching agents after eight years with the same carrier. The incumbent carrier is slow to release updated loss runs, and the new agency submits the account to market using two-year-old data showing three open claims. Markets quote conservatively based on stale, inflated reserves, and the contractor’s premium comes in 40% higher than it should. Once corrected loss runs arrive showing two of the three claims closed with no payment, the account re-rates significantly lower.
How Does Loss Runs Work?
- The request. An agency or policyholder requests loss runs from the current or prior carrier, usually through the underwriter or a dedicated loss run request line.
- The pull. The carrier’s claims system generates a report covering the requested policy period, pulling claim number, date, cause, reserve, and payment data.
- The delivery. The carrier sends the report to the requesting party, often by email or through an online portal, sometimes with a turnaround delay of one to two weeks.
- The review. The agency or underwriter reviews the report for accuracy, checking whether reserves reflect current claim status and whether closed claims are marked correctly.
- The application. Underwriters use the verified loss history to price the account, calculate experience modification impact, and decide on coverage terms or exclusions.
Real Claim Examples Involving Loss Runs
Habitational property with an unreported reserve reduction
A multi-family apartment owner had a slip-and-fall claim reserved at $150,000 for a fractured hip. The claim settled for $35,000 eighteen months later, but the carrier’s loss run was never updated to reflect the reduced reserve when the agency requested it for a renewal marketing effort. Underwriters at three competing carriers quoted the account as if the full reserve were still active, and the owner nearly accepted a renewal 25% above market before the agency caught the discrepancy and requested a corrected report.
Trucking fleet with duplicate claim entries
A regional trucking company’s loss runs showed what appeared to be twelve claims over three years, but closer review revealed four claims had been double-entered under both the auto liability and general liability lines because of a coding error at the carrier’s claims department. The inflated count pushed the account into a higher-hazard underwriting tier. The agency flagged the duplicates, obtained a corrected report from the carrier’s claims supervisor, and the account moved back into standard pricing.
Contractor denied coverage over missing loss runs
A general contractor applying for a wrap-up policy on a large commercial project could not produce loss runs from a carrier that had gone into receivership three years earlier. Without verifiable loss history, the wrap-up underwriter assumed worst-case experience and declined to offer competitive terms. The contractor eventually obtained a loss history affidavit from the state guaranty association, but the delay cost weeks on a time-sensitive bid.
Loss Runs vs. Experience Modification Factor: What Is the Difference?
Loss runs are the raw documentation of individual claims, while the experience modification factor is a calculated number derived largely from workers’ compensation loss run data. Loss runs cover every line of business and show claim-level detail; the experience modification factor is a single multiplier applied specifically to workers’ compensation premium.
| Comparison area | Loss Runs | Experience Modification Factor |
|---|---|---|
| Primary use case | Documenting claim-by-claim history for underwriting review | Adjusting workers’ compensation premium based on past loss experience |
| Coverage / concept type | Raw claims data report | Calculated rating factor |
| Typical exclusions | May omit claims under a carrier’s reporting threshold | Excludes medical-only claims above a certain severity split in some states |
| Who is most affected by errors | Any policyholder being marketed to new carriers | Employers subject to mandatory experience rating, typically mid-size and larger accounts |
| Common mistakes | Accepting stale or inflated reserves without verification | Assuming the mod is correct without checking underlying loss runs |
What Are the Most Common Mistakes With Loss Runs?
- Treating open reserves as final numbers, which overstates true loss cost and leads to higher renewal quotes than the actual experience justifies.
- Waiting until days before renewal to request loss runs, leaving no time to dispute errors or shop the account properly.
- Failing to request loss runs from every prior carrier when a client has switched insurers multiple times, creating gaps that look like missing history to underwriters.
- Submitting loss runs to market without a narrative explaining large or unusual claims, letting underwriters assume the worst about a one-time event.
- Overlooking claims that were later subrogated or recovered, which should reduce the net incurred amount but often remain unadjusted on the report.
- Assuming a carrier will automatically send updated loss runs after a claim closes, when in practice agencies must proactively request refreshed reports.
How to Explain Loss Runs to a Client
Explaining Loss Runs to a personal lines client
Loss runs work a lot like a driving record, except they track your insurance claims instead of tickets. Insurance companies look at your claim history to decide how much to charge you, so the fewer and smaller the claims, the better your pricing tends to be. We pull these reports whenever we shop your policy to make sure the carriers see an accurate picture.
Explaining Loss Runs to a small business owner
Loss runs are the report card insurance companies use to see how many claims your business has had and what they cost. Every time we market your policy to a new carrier, we send them your loss runs so they can price you fairly based on real history, not guesswork. If any of those numbers look wrong, like an old claim still showing a big reserve, we push back and get it corrected before it affects your premium.
Explaining Loss Runs to a CFO or risk manager
Loss runs are the claim-level data carriers use to underwrite your program, broken out by date of loss, cause, incurred amount, and current reserve status. We review these line by line before every renewal because reserve inflation on open claims can distort your experience modification and overall pricing for multiple policy periods. Our process includes requesting corrected reports whenever reserves don’t reflect current claim status, which directly protects your total cost of risk.
Frequently Asked Questions About Loss Runs
How far back do loss runs typically go?
Most carriers provide loss runs covering three to five years, which aligns with the lookback period underwriters generally use to assess risk. Some larger accounts or those in high-hazard industries may request or receive data going back further. Workers’ compensation loss runs often align with the same period used for experience modification calculations.
Who can request loss runs from a carrier?
The named insured, the agent of record, or an authorized representative can typically request loss runs directly from the carrier or its claims department. Some carriers require written authorization from the policyholder before releasing data to a new agent. Total CSR’s training work with agencies shows that delays most often happen when authorization paperwork is incomplete, not when carriers are being difficult.
What happens if a carrier refuses to provide loss runs?
Carriers are generally expected to provide loss runs upon reasonable request, though state regulations on timing and format vary. If a carrier has gone insolvent or stopped operating, the policyholder may need to contact the state guaranty association that assumed its obligations. Persistent delays should be escalated through the underwriter rather than the claims department, since underwriters have more incentive to resolve the issue quickly.
Can loss runs affect my experience modification factor?
Loss runs feed directly into the experience modification calculation for workers’ compensation, since the rating bureau uses reported claim data to compute the mod. Errors on loss runs, such as a claim coded to the wrong classification or an inflated reserve, can distort the mod and raise premium unfairly. Reviewing loss runs before the bureau’s calculation deadline gives time to request corrections.
Why do open claims hurt pricing even if they never get paid out?
Underwriters price based on incurred losses, which include reserves on open claims, not just amounts actually paid. A large reserve signals potential future cost, so underwriters factor it into pricing even if the claim eventually closes for less or for nothing. This is why reviewing and challenging inflated reserves before marketing a renewal matters so much.
Do loss runs include claims with no payment at all?
Loss runs typically include every reported claim, even those closed without any payment, because the report is meant to show full claim activity. A claim closed at zero dollars still demonstrates how the policyholder and carrier handled an incident. Underwriters generally view a high frequency of zero-payment claims more favorably than a smaller number of large paid claims.
Related Insurance Terms
- Experience Modification Factor: A rating multiplier applied to workers’ compensation premium based on a policyholder’s historical loss experience compared to industry peers, calculated largely from loss run data.
- Underwriting: The process carriers use to evaluate and price risk, relying heavily on loss runs to assess a policyholder’s claim history before quoting coverage.
- Loss Reserve: The estimated amount a carrier sets aside to pay a claim before it closes, appearing as a line item on every loss run and directly affecting renewal pricing.
- Certificate of Insurance: A document summarizing active coverage, distinct from loss runs because it shows current policy limits rather than historical claim activity.
- Claims History: The broader record of a policyholder’s past losses across all carriers and policy periods, of which loss runs are the primary documented source.
- Third-Party Administrator: An organization that manages claims on behalf of a self-insured employer or captive, often the source of loss runs for those programs instead of a traditional carrier.
Sources and References
- International Risk Management Institute (IRMI). Loss Run Reports Explained.
About the Author
Justin Goodman, CIC, CCIP, CISC, CLCS, CRIS, PCIA, QCLS, MFHR CEO and Co-Founder, Total CSR, Inc.
Justin Goodman is a third-generation insurance broker with over two decades in agency operations. He has trained more than 100,000 CSRs, account managers, and producers in commercial and personal lines coverage, from workers’ compensation to construction risk. He was named 2024 Insurance Journal Agent of the Year and one of the nation’s top five construction insurance experts by Risk & Insurance. He is the author of Retain, which applies cognitive science research on memory and knowledge transfer to insurance training, and speaks nationally on how agencies build durable technical expertise in their teams.