Workers' Comp Loss Runs

What a comp loss run shows that other lines don't

Most of a loss run looks the same across lines of business. Workers' comp adds detail that underwriters read closely:

• Indemnity vs. medical split — paid and reserved amounts broken out separately. A book that is mostly medical-only reads very differently from one carrying lost-time claims at the same total dollars.
• Claim type — medical-only against lost-time (indemnity). Frequency of medical-only claims signals safety-programme problems; lost-time claims drive the premium.
• Nature of injury and body part — often coded. Repeated soft-tissue back claims tell a different story than one severe machinery incident.
• Date of injury vs. date reported — a long gap between the two is a reporting-discipline red flag and inflates future reserve development.
• Return-to-work or disability status — shown by some carriers; absent on others.
• Subrogation and recovery — where recoveries have reduced net incurred.

Loss run vs. experience mod worksheet

Agents are regularly asked for "the mod" and sent a loss run, or the reverse. They are different documents from different sources and they will not reconcile.

	Loss run	Experience mod worksheet
Comes from	The carrier	NCCI or the state rating bureau
Shows	Every claim, as valued today	Capped and split losses used in the mod calculation
Valuation	Whatever date you requested	Fixed — normally six months before the rating effective date
Years included	Whatever you asked for, usually five	Typically three completed policy years, excluding the most recent
Used for	Underwriting, marketing, reserve review	Calculating the experience modification factor

If the numbers don't match, that is expected — not an error in either document. Different valuation dates and the mod's loss-capping rules guarantee a gap.

Why valuation dates matter most on this line

Workers' comp is a long-tail line. A claim reported this year can still be developing four years from now as medical treatment, permanent disability awards or litigation play out. That means reserves move more, and faster, than on property or auto.

The practical effect: comp submissions routinely carry the tightest valuation windows in the market. Where a general liability submission might accept loss runs valued within 90 days, comp underwriters frequently want 60 or 30. See what "currently valued" means and how tight the windows get →

How many years to request

• Five years — the standard submission requirement, and what to ask for by default.
• Three years — sometimes accepted on small accounts, but it will not show trend across a full market cycle.
• Ten years — occasionally required where there is a history of severe claims or on programme business with heavy retention.

If the account has moved carriers during that window, every prior carrier needs its own request. That is the part that turns a renewal into a two-week paperwork exercise.

What underwriters look for

• Frequency — number of claims relative to payroll and class code. High frequency at low severity still signals a safety problem.
• Severity — individual large losses, and whether they were one-off events or a pattern.
• Open claim reserves — uncertain future cost. Large open reserves on old years make underwriters cautious.
• Trend direction — improving, flat or deteriorating. A book trending down after a safety programme is a story worth telling in the submission.
• Claims closed with no payment — high counts can indicate over-reporting or a litigious environment.

Requesting comp loss runs

Requests go to the carrier's claims department or agent portal, and the request should name the years and the valuation window explicitly rather than asking for "current" loss runs. For state funds and the monopolistic states, the route is the fund's own process rather than a carrier inbox, and turnaround is usually slower.

Look up the carrier in our directory for contact route, required information and accepted formats, or read the full how-to guide.

Getting the data out of the PDF

Comp loss runs are among the densest a carrier produces — more columns than any other line, often across many pages, and formatted differently by every carrier. Re-keying them into a spreadsheet or submission package is the part of the renewal nobody has time for.

LossRunGuru is built to read carrier loss run PDFs and return the claims as structured data. See how it works →

Related: what a loss run report is, an annotated example, and general liability loss runs.