Anti-Concurrent Causation: The Clause That Excludes Everything at Once

Hurricane damage is never one thing: wind tears the roof while surge floods the first floor. Anti-concurrent causation (ACC) clauses say that when a covered peril and an excluded peril combine to cause a loss, the exclusion wins — the entire loss. It's the most consequential sentence in coastal property insurance, and most policyholders have never heard of it.

What the clause says

Typical ACC language: 'We do not cover loss caused directly or indirectly by [excluded peril], regardless of any other cause or event contributing concurrently or in any sequence to the loss.' The key phrase is 'in any sequence' — it doesn't matter if the covered peril (wind) came first and the excluded one (flood) second. If the excluded peril contributed, the clause excludes everything it touched.

The clause usually sits in front of the big exclusions: flood, earth movement, and sometimes mold or wear and tear.

Why it matters most after hurricanes

After a hurricane, nearly every property has both wind and water damage, and they're physically tangled — did the roof fail from wind before the surge arrived, or did water enter first? Carriers have a structural incentive to maximize the flood attribution, because every dollar assigned to flood is a dollar the homeowners policy doesn't pay.

This is why the sequence documentation matters enormously: photos timestamped during the wind phase, before water intrusion, separate the covered loss from the excluded one.

Where courts have pushed back

ACC clauses have been litigated heavily, especially after major hurricanes, with mixed results that vary by state:

Some courts enforce ACC clauses as written — the exclusion stands.
Others require the carrier to prove the excluded peril was the efficient proximate cause — the dominant force setting the chain in motion — regardless of the clause.
A few states limit ACC application by statute or regulation.

The takeaway isn't a universal rule — it's that the clause is contested terrain, not settled law. A denial letter treating ACC as the final word deserves a second opinion from a licensed attorney in your state.

Fighting an ACC-based denial

Separate the damage: an engineer's report distinguishing wind damage from flood damage is the gold standard.
Document sequence with timestamped photos and weather data showing when wind vs. surge hit your location.
Challenge the flood attribution specifically — carriers sometimes label ambiguous water damage as 'flood' by default.
Research your state's treatment of ACC clauses; the case law genuinely differs.
Bring an attorney early for large ACC disputes — this is legal-territory argument about causation, not a paperwork appeal.

What to do before the next storm

Know whether your policy contains ACC language and which perils it fronts — read the exclusions section, not just the declarations.
Carry flood insurance if you're anywhere near water — ACC disputes shrink dramatically when both perils are covered somewhere.
Set up timestamped photo documentation of your property's condition before hurricane season.
Understand your wind/hail deductible vs. your flood deductible — they're different numbers on different policies.

The denial you'd never lose

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Common questions

Can the carrier really deny wind damage just because there was also flooding?

Under a broadly written ACC clause, that's exactly what it attempts. Whether it holds depends on your state's law, the specific damage, and how well you separate the wind loss from the flood loss with evidence.

What is 'efficient proximate cause'?

The legal doctrine that identifies the dominant cause setting a loss in motion. In some states it overrides ACC clauses — if wind was the efficient proximate cause, the loss is covered even with flood in the mix. In other states, the clause wins. It's state-specific.

Should I file with both my homeowners and flood carriers?

Yes — file with both promptly. Let each carrier evaluate its portion rather than letting one carrier's flood attribution decide everything unchallenged.

Does ACC apply to non-hurricane claims?

The clause is in the policy year-round, but it matters most where covered and excluded perils physically combine — hurricanes, wildfires followed by mudslides, earthquakes followed by fire. Read which exclusions your ACC language fronts.

Keep reading

Educational content, not legal advice. Deadlines, rules, and coverage vary by state, carrier, and policy — read your policy and consult a licensed professional for your situation.