Occurrence Policy: Definition and How It Works
An occurrence policy is an insurance policy that covers claims arising from an incident that occurs during the policy period, regardless of when the claim is actually filed. As long as the bodily injury, property damage, or covered event took place while the policy was in force, the insurer must respond — even if the claim is filed years or decades after the policy has lapsed or been cancelled. Occurrence coverage is the standard trigger for Commercial General Liability (CGL) policies, workers' compensation policies, and most commercial property insurance. It is the opposite of claims-made coverage, where the claim must be filed while the policy is active.
How the Occurrence Trigger Works
Under an occurrence-trigger policy, the coverage analysis involves two questions:
- Did the incident (occurrence) happen during the policy period? — If yes, the policy potentially responds.
- Does the claim fall within the covered causes and within the policy limits? — If yes, the insurer defends and indemnifies.
The date the claim is filed is irrelevant to whether coverage attaches. A CGL policy that was in force in 2020 will respond to a bodily injury claim filed in 2026, provided the injury-causing incident happened during the 2020 policy period.
This "once covered, always covered" characteristic is the defining advantage of occurrence coverage. It eliminates the need for tail coverage, provides permanent protection for prior acts, and simplifies coverage continuity decisions when a client changes insurers.
Where Occurrence Coverage Is Used
Occurrence trigger is standard for:
- Commercial General Liability (CGL): Bodily injury and property damage from business operations, premises, and products (ISO CG 00 01 form)
- Workers' Compensation: Employer liability coverage for employee injuries
- Commercial Property: Damage to buildings and contents
- Business Owners Policy (BOP): The CGL component uses occurrence trigger; see Business Owners Policy for how BOP is structured
- Commercial Auto: Bodily injury and property damage from vehicle use
- Umbrella/Excess Liability: Typically follow the form of the underlying policy — occurrence trigger for umbrellas sitting above CGL
Occurrence vs Claims-Made: Key Differences
| Feature | Occurrence Policy | Claims-Made Policy |
|---|---|---|
| Coverage trigger | Incident occurs during policy period | Claim filed during policy period |
| Tail coverage needed? | No | Yes, when policy is cancelled/non-renewed |
| Retroactive date | Not applicable | Critical — sets earliest covered act date |
| Typical use | CGL, property, workers' comp | E&O, D&O, cyber, medical malpractice |
| Coverage for past acts | Permanent once a policy covered the period | Only if retroactive date covers the act |
| Premium behavior | Generally stable year-to-year | May increase as claims history matures |
Long-Tail Liability and Occurrence Policies
A critical characteristic of occurrence policies is that they can generate claims long after the policy expires — sometimes decades later. This is especially relevant for:
- Products liability: A manufacturer's product causes injury years after sale
- Construction defects: A building defect manifests 10 years after completion
- Environmental contamination: Pollution that began in 1995 surfaces as a claim in 2020
- Asbestos, silica, and other latent injuries: Bodily injury from prolonged exposure with a delayed discovery of harm
This long-tail exposure is why insurers price occurrence-form CGL carefully for industries with extended liability horizons (construction, manufacturing, chemicals). For clients in these industries, brokers must ensure that prior-period occurrence policies are preserved and accessible — a client that retroactively loses its old occurrence policies in a corporate transaction may lose decades of coverage.
Occurrence Coverage for Professional Service Businesses
Most professional liability (E&O) and Directors & Officers (D&O) policies do NOT use occurrence triggers — they are claims-made. This creates a common coverage gap: a professional service firm's CGL policy (occurrence) covers premises and operational liability, but its E&O policy (claims-made) covers professional errors on a different trigger. Understanding the interaction is essential when a loss touches both policies.
For a complete comparison of occurrence vs claims-made coverage mechanics and the scenarios where each applies, see Occurrence vs Claims-Made E&O Coverage.
Related Terms
- Claims-Made Policy — the alternative trigger used for professional liability, D&O, and cyber coverage; requires active policy at the time of the claim
- Errors and Omissions Insurance — professional liability coverage that almost universally uses a claims-made trigger rather than occurrence
- Additional Insured — additional insureds on occurrence-form CGL policies have ongoing protection for covered incidents during the policy period even after the policy expires
How Brokers Use Occurrence Policies in Practice
Brokers rely on occurrence trigger as the default for CGL placement and use it to explain coverage continuity to clients. When a client asks "what happens to my coverage if I switch insurers?" — for CGL, the answer is straightforward: the old occurrence policy covers prior incidents permanently. For E&O, the answer is more complex and involves retroactive dates and tail endorsements. Teaching clients this distinction is a core part of the account review process and helps brokers justify the importance of maintaining prior E&O policies on a claims-made form.