Anti-Concurrent Causation Clause

An anti-concurrent causation clause is a lead-in provision, usually attached to a group of property exclusions, stating that the insurer will not pay for loss caused directly or indirectly by an excluded peril, whether or not any other cause or event contributes concurrently or in any sequence. In plain terms, if an excluded peril is part of the causal chain at all, the entire loss is excluded — even if a covered peril was the main driver. It exists specifically to reverse the policyholder-friendly result that the concurrent causation doctrine would otherwise produce.

For a small-business buyer, an ACC clause can dramatically shrink what a property policy actually pays after a mixed-cause catastrophe. The most common battleground is storm damage: if wind (often covered) and flood (typically excluded) both damage a building, an ACC clause can allow the insurer to deny the full loss because the excluded flood contributed. This is why relying on a standard property form for catastrophe exposure is risky, and why standalone flood or earthquake policies are often essential rather than optional.

The important nuance is that ACC clauses are not enforced uniformly. Some states uphold them as written, giving exclusions sweeping effect; others hold that a mandatory efficient-proximate-cause rule overrides the clause, so a covered predominant cause still triggers coverage. The specific wording and its placement relative to the exclusions also affect enforceability. Buyers should ask their broker whether their form contains ACC language, understand how their state treats it, and fill the resulting gaps with dedicated flood, earthquake, or difference-in-conditions coverage before a loss occurs.