How does a summer lost-time claim affect my experience modification rate?

A lost-time claim enters your experience rating worksheet at the value the carrier assigns. The first dollars, up to your state's split point (typically $15,000 to $25,000 in NCCI states), hit the primary loss layer at full actuarial weight. Primary losses carry the most weight in the mod formula. Because the formula punishes frequency, a burst of three or four summer claims can raise your mod more than a single large claim at any other time of year.

Why are first-year construction employees more likely to get hurt in summer?

Contractors hire heavily for summer backlogs, putting the least experienced workers on site during the highest-risk months. Travelers found first-year workers account for 44% of construction injuries (Travelers, May 2026). WCRI data shows workers with two months or fewer of tenure have the highest heat illness incidence of any group. The overlap between onboarding season and heat season is the core of the problem.

Does an OSHA heat inspection change my workers' comp mod?

Not directly. OSHA citations and penalties are separate from your experience modification rate. But the heat event that triggers an OSHA inspection typically generates the workers' comp claim that does affect your mod. OSHA's revised Heat NEP (April 2026) authorizes inspections on heat advisory days, so enforcement activity and claim-generating incidents often overlap.

How long do summer claims stay on my experience rating worksheet?

Claims stay on your NCCI worksheet for three full policy years, excluding the most recent year. A cluster of summer claims in 2026 first appears on your mod calculation for the policy year beginning in 2028 and doesn't roll off until 2031. One bad summer can inflate your mod across three consecutive renewal cycles.

What share of construction workers' comp claims come from heat illness?

Construction accounts for 21% of all heat-related workers' comp claims nationally, roughly triple its 7% share of overall claims (WCRI, 2024). Three out of four heat illness claims occur between June and August. While heat illness is a small fraction of total construction claims by count, these incidents often escalate into costly lost-time claims when they trigger falls or cardiac events on the job.

Field ReportJune 2026 · 4 min read

Peak Season Construction Claims: June to September Sets Your Mod

June through September drives more construction lost-time claims than any other stretch. Heat, new hires, and rising severity converge, and the mod formula counts every one.

By TraciThe Orson Group

Field Report

+13%

Construction medical claim severity increase, accident year 2024

NCCI SOL Guide 2026

At a glance

June through September is when construction workers' comp claims peak. Heat illness claims rise sevenfold above 90°F (WCRI, 2024), first-year employees account for 44% of construction injuries (Travelers, 2026), and longer shifts extend exposure. Each lost-time claim that crosses the primary loss threshold hits your experience modification rate at full actuarial weight. Summer sets your mod for the next three years.

What if the four months that fill your backlog are the same four months that inflate your mod?

For Southeast construction contractors, peak season means June through September. It's when heat illness, new-hire injuries, and rising medical severity converge on the same worksheet. The peak season construction claims that result don't just add up. They compound. The mod formula weighs each one individually, and frequency punishes harder than severity.

Your experience modification rate (EMR, also called "the mod") runs on three years of claim data under the system administered by NCCI (the National Council on Compensation Insurance). Each claim's first dollars, up to the state-specific split point, hit the primary loss layer at full actuarial weight. Five $10,000 claims damage a mod more than one $50,000 claim. That math makes a concentrated burst of summer claims especially destructive.

Heat illness and the sevenfold multiplier

The Workers Compensation Research Institute (WCRI) published its heat illness FlashReport in December 2024, covering 31 states from 2013 to 2022. The core finding: heat-related illness claims rise at least sevenfold on days above 90°F compared to days between 75°F and 80°F (WCRI FlashReport FR-24-04, December 2024). Above 100°F, the multiplier reaches 18x.

Construction takes 21% of all heat-related workers' comp claims, triple its 7% share of overall claims (WCRI, 2024). Three out of four heat illness claims land between June and August. For a contractor running crews in Charlotte, Birmingham, or Jacksonville, the calendar alone creates the exposure.

These claims rarely stay small. A heat event that leads to a fall, an equipment incident, or a cardiac episode turns into a lost-time claim that crosses the primary threshold. Stack two or three in a single summer, and the mod impact compounds across the next three rating periods.

New hires land in the hottest weeks

Travelers analyzed more than 1.2 million workers' comp claims from 2021 to 2025 and found that first-year employees account for 44% of all construction injuries and 47% of construction claim costs (Travelers Injury Impact Report, May 2026). Injured first-year construction workers average 114 lost workdays, compared to 80 days across all industries.

Peak season is also peak hiring season. Contractors staff up for summer backlogs, and the newest workers face the highest ambient temperatures with the least site-specific knowledge. WCRI's data confirms the overlap: workers with two months or fewer of tenure have the highest heat illness incidence of any cohort.

OSHA's revised Heat National Emphasis Program (NEP), reissued April 10, 2026, runs for five years and targets 55 high-risk industries, construction among them (OSHA CPL 03-00-024, April 2026). Between April 2022 and December 2024, OSHA conducted roughly 7,000 heat-related inspections and issued nearly 1,400 Hazard Alert Letters. An OSHA citation doesn't change your mod directly. But the incident that draws the inspector usually generates the claim that does.

Rising severity makes each claim costlier

NCCI's 2026 State of the Line Guide reported a 13% jump in construction medical claim severity for accident year 2024 (NCCI SOL Guide, May 2026). Over half of the top 10 construction classes saw double-digit severity increases. The claims your crews file this summer cost more per incident than last summer's did.

Higher per-claim severity raises the dollar amount hitting the primary layer. A claim that resolved at $8,000 two years ago may now resolve at $12,000 or $15,000, pushing deeper past the split point and carrying more weight in the formula. In our reviews of Southeast contractor worksheets, the pattern is consistent: a disproportionate share of primary losses cluster in the June through September window. Rising severity on top of peak-season frequency is the combination that moves mods.

ABC Carolinas published its heat illness prevention framework on June 1, 2026, calling for written heat plans with triggers at 80°F heat index and high-heat protocols at 90°F (ABC Carolinas, June 2026). Programs like these work because they target the mechanism behind the claims: unacclimatized workers doing full shifts in conditions their bodies aren't ready for. The financial case for running one isn't about avoiding a fine. It's about keeping four months of claims off three years of worksheets.

What an audit would check

An audit looks at whether open claims from prior summers carry current medical values or stale reserves set during the initial event. It checks whether claims coded as lost-time actually resulted in lost time, whether classification codes match the work performed during peak season, and whether any heat-related claims carried subrogation potential that was never pursued.

If your mod climbed after a rough summer and hasn't come back down, send us your NCCI worksheet and we'll tell you whether the data behind it is accurate.