Anti-Concurrent Causation Clause
An anti-concurrent causation clause excludes coverage for losses involving an excluded peril even when a covered peril occurs simultaneously or in sequence and contributes to the same damage.
The anti-concurrent causation (ACC) clause is one of the most significant and often misunderstood provisions in commercial property insurance. It appears in the exclusion section of most ISO and manuscript property forms and states that losses are excluded when an excluded peril acts concurrently or in any sequence with a covered peril to produce the damage. The practical effect is that if flood (an excluded peril) and wind (a covered peril) both contribute to a loss during a hurricane, the insurer can deny the entire claim under the ACC clause, even though wind damage alone would be covered.
This clause became a focal point of insurance litigation after Hurricane Katrina, when thousands of property owners argued that wind damage should be covered separately from flood damage. Courts have reached different conclusions depending on jurisdiction, but the majority have upheld ACC clauses as written, reinforcing the importance of purchasing separate flood coverage. For apartment owners in coastal or flood-prone areas, the ACC clause means that relying solely on a property policy with standard flood exclusions creates a significant coverage gap during weather events that combine wind, rain, and storm surge.
Apartment owners should review their property policy's ACC language carefully and discuss it with their broker. Some carriers offer modified ACC clauses or concurrent causation language that provides more favorable treatment when covered and excluded perils combine. Purchasing standalone flood and earthquake policies is the most reliable way to mitigate the risk created by ACC clauses, ensuring that each peril has its own dedicated coverage rather than relying on arguments about which peril caused which portion of the damage.