A hurricane tears shingles from a roof, then storm surge floods the rooms below. Both forms of damage came from the same storm, but an insurer may treat them very differently. One reason is the insurance anti concurrent causation clause, a policy provision that can restrict coverage when a covered cause and an excluded cause contribute to the same loss.
These disputes are not simply about which event happened first. They turn on the exact policy wording, how the damage occurred, and the law governing the claim. Understanding those distinctions makes it easier to read an exclusion and recognise why an adjuster might separate one part of a property claim from another.
What Does an Anti-Concurrent Causation Clause Do?
An anti-concurrent causation clause, often shortened to ACC clause, generally says that specified losses remain excluded even when another cause contributes at the same time or in a sequence of events. It usually appears alongside particular property exclusions, such as flood or earth movement, rather than applying automatically to every exclusion in the contract.
Read the Policy in Three Layers
Start with the coverage grant
Determine what property and causes of loss the policy initially covers. A named-perils policy lists covered risks; an open-perils form generally covers direct physical loss unless a limitation or exclusion applies. Deductibles, conditions, and separate coverage sections can still affect payment.
Identify the actual exclusion
Next, locate the property exclusion the insurer relies on. Flood, surface water, seepage, deterioration, and earth movement may be defined or limited differently. A water exclusion, for example, should not be assumed to cover every type of water damage. Read definitions, exceptions, and any ensuing-loss wording together.
Check whether ACC wording governs that exclusion
The phrase about causes acting concurrently or in any sequence may introduce only a specific group of exclusions. Its placement is significant. An ACC clause attached to flood exclusions does not necessarily control an unrelated provision elsewhere in the contract. Also check endorsements issued with the policy: they may add, remove, or amend exclusions.
A Storm Claim: Separate Damage Is Not the Same as Combined Damage
Imagine powerful wind breaks roof tiles before rising coastal water enters the ground floor. A roof inspection documents wind damage that occurred independently of flooding. Photographs also show floodwater damaging flooring and cabinets. Finally, one interior wall suffered damage from both wind-driven effects and floodwater.
Under a policy that covers wind but excludes flood with enforceable ACC language, the independently wind-damaged roof may remain covered, while the flood damage and jointly caused wall damage may be excluded. The entire claim is not necessarily denied merely because flooding occurred on the property. The critical question is which causes produced each distinct item of damage.
This distinction appeared in Leonard v. Nationwide Mutual Insurance Co., a 2007 federal appellate decision involving Hurricane Katrina in Mississippi. The court treated damage caused solely by wind differently from damage caused by excluded water or by wind and water acting together. It also upheld the relevant ACC wording under its interpretation of Mississippi law.
How ACC Clauses Interact With Causation Rules
Under the efficient proximate cause approach, attention centres on the predominant cause that set the loss in motion. Where applicable, a covered predominant cause can support coverage despite another contributing excluded cause. The concurrent cause approach, in some circumstances, permits coverage when independent covered and excluded causes combine and neither can reasonably be singled out as predominant.
Contract terms can change how these default doctrines apply. The anti concurrent causation wording commonly seeks to exclude a loss when a specified excluded peril contributes, even though another event would otherwise be covered. Still, a claim must be evaluated under the actual policy and the jurisdiction’s law, rather than a universal rule.
Why State Law Can Change the Outcome
US insurance policies are interpreted under applicable state law, so a conclusion reached in one state should not be treated as nationwide precedent. California, for example, applies the efficient proximate cause doctrine through Insurance Code section 530. Its Supreme Court has addressed both limits on exclusions and an insurer’s ability to define particular combinations of events as excluded risks, including in Julian v. Hartford Underwriters Insurance Co. (2005).
Florida’s Supreme Court applied concurrent causation reasoning in Sebo v. American Home Assurance Co. (2016), involving a home damaged by multiple perils. That decision concerned the policy language before the court; it does not mean every Florida claim involving covered and excluded causes must be paid regardless of an ACC provision.
The practical lesson is to avoid broad claims that ACC clauses are always enforceable or always invalid. Policy wording, state statutes, controlling decisions, the type of peril, and the evidence all matter. For a substantial disputed claim, a licensed insurance professional or attorney familiar with the relevant state can assess the particular language.
What to Document When Multiple Causes Are Suspected
Begin with a room-by-room or component-by-component damage record. Note when damage was first observed, photograph water lines and openings in the building, retain weather information, and preserve inspection reports or repair estimates. Where safe, keep damaged materials or clear photographs before disposal. The aim is to establish what happened to each item, not simply to prove that a major storm occurred.
Ask the insurer to identify the specific policy section supporting each disputed decision and explain which cause or causes it attributes to that damage. Compare the denial letter with the declarations, complete form, and endorsements. If a technical causation dispute remains, an appropriate engineering or other specialist assessment may help clarify the sequence.
Frequently Asked Questions
Does an ACC clause mean a claim with two causes is automatically denied?
No. The excluded peril must fall within the relevant provision, and the clause must apply under governing law. Damage caused separately by a covered peril may still qualify. Each component of the loss deserves its own causation analysis.
Is concurrent causation the same as efficient proximate cause?
No. Concurrent causation focuses on multiple contributing causes in circumstances defined by applicable law. Efficient proximate cause seeks the predominant cause of the loss. Courts do not apply these doctrines identically across states.
Can wind damage be covered when flood damage is excluded?
Yes, depending on the policy and evidence. Distinct wind-only damage may be covered even where an ACC provision excludes flood-related or jointly caused damage. The precise scope of wind, water, and flood coverage must be checked.
Where can I find an anti-concurrent causation clause?
Look within the exclusions section, especially introductory wording preceding listed causes of loss. Review endorsements as well. If the terminology is unclear, request an explanation referencing the exact provision rather than relying on a general summary of coverage.
The Key Is the Damage, Not Just the Disaster
An insurance anti concurrent causation clause can have a decisive effect on complex property claims, but it does not erase the need to identify the actual causes of each loss. Start with the coverage grant, read the exclusion and its qualifying language, and then examine the physical evidence under the applicable state law. That method produces a more reliable answer than assuming one covered event—or one excluded event—determines the outcome for the whole property.