Occurrence-basis liability coverage is tied to when the incident happened, not when the claim is filed.
Why it matters
If an event occurred during the policy period, the insurer generally remains responsible even if the lawsuit or demand appears after policy expiry, subject to policy wording and limits.
Claims and underwriting impact
Because this coverage can create long-duration exposure, underwriters often price it more conservatively than claims-made versions. Limits, exclusions, and aggregate ceilings are calibrated to late-reporting risk.
Scenario
A medical error in Year 1 causes injuries discovered in Year 3. If that medical practice bought occurrence coverage in Year 1, the claim may still be within coverage because the event occurred during the active term.