Definition:Co-insurance clause
📄 Co-insurance clause is a policy provision that requires the policyholder to maintain coverage at or above a specified percentage of the property's actual or replacement value — most commonly 80%, 90%, or 100% — as a condition of receiving full indemnification for a partial loss. Widely used in property insurance across many global markets, the clause is designed to discourage underinsurance and ensure that premiums collected are commensurate with the true value at risk. While the term "co-insurance" is used differently in health insurance contexts — where it refers to the insured's percentage share of each covered expense — in property insurance the co-insurance clause specifically addresses the adequacy of the sum insured relative to the property's value.
⚙️ When a loss occurs, the insurer tests whether the policyholder has met the co-insurance requirement. If the amount of insurance carried equals or exceeds the stipulated percentage of the property's value at the time of loss, the claim is paid in full (subject to the deductible and policy limit). If the policyholder has insured below that threshold, the insurer applies a penalty proportional to the shortfall: the formula typically divides the amount of insurance actually carried by the amount that should have been carried, then multiplies that ratio by the loss. For example, under an 80% co-insurance clause, a property worth $1 million that is insured for only $600,000 would result in the policyholder bearing a proportional share of any partial loss — effectively self-insuring the gap. This mechanism is standard in North American commercial property markets, while analogous "average clauses" and "condition of average" provisions serve the same function in the UK, European, Asian, and Latin American markets. Some policies offer a co-insurance waiver or an agreed-value endorsement, under which the insurer and policyholder agree on the property's value at inception, removing the risk of a co-insurance penalty at the time of claim.
💡 Properly understanding co-insurance clauses is essential for brokers advising clients and for underwriters pricing risk, because the clause directly affects how losses are allocated between insurer and insured. Policyholders who fail to update their coverage as property values appreciate — a persistent issue in inflationary environments — may find themselves penalized at the worst possible moment: when they file a claim. For insurers, the co-insurance clause acts as a safeguard against adverse selection, since without it, policyholders could rationally insure for far less than full value and still recover partial losses dollar-for-dollar, paying inadequate premium for the exposure the insurer assumes. The clause thus underpins the principle of indemnity and maintains equitable premium-to-risk relationships across the property insurance portfolio.
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