The 80% Coinsurance Clause and the Signed Rejection
A Kentucky retailer owns a building with a replacement cost of $1,600,000 and inventory that cost $40,000 (depreciated value $25,000). To hold down premium, the owner and agent agree on a commercial property policy with a $1,000,000 building limit, an 80% coinsurance clause, replacement cost on the building, actual cash value on stock, and a $5,000 deductible. The agent's file contains the owner's signed acknowledgment rejecting a recommended limit of $1,280,000. In June a fire destroys one wing: replacement cost of the damage is $300,000, of which $100,000 is attributable to depreciation. The damaged stock is a total loss. The owner expects a check for $300,000 for the building plus $40,000 for the stock.
1. Calculate what the policy pays for the building damage and show each step.
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Step 1 - Insurance required to satisfy the coinsurance clause. 80% × $1,600,000 replacement cost = $1,280,000
Step 2 - The ratio (did ÷ should). $1,000,000 ÷ $1,280,000 = 0.78125
Step 3 - Apply the ratio to the loss. Because the limit is below the coinsurance requirement, payment is reduced proportionally: 0.78125 × $300,000 = $234,375
Step 4 - Apply the deductible. $234,375 − $5,000 = $229,375
Step 5 - Check the limit. $229,375 is well under the $1,000,000 limit, so the limit does not cut the payment further.
Building payment: $229,375.
Why replacement cost, not ACV, is the measure: the policy insures the building on a replacement cost basis, so the $100,000 of depreciation is not subtracted. That is a separate benefit the insured bought; it does not cure the coinsurance shortfall.
Note on method: some forms apply the deductible to the loss before the ratio. Expect a difference of a few thousand dollars and state the assumption you used - carriers vary, and the calculation should be shown either way.
2. Calculate the total payment for building and stock, and quantify in dollars what the inadequate limit cost the owner.
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Stock. Inventory is insured on an actual cash value basis, so depreciation is deducted: $40,000 cost − $15,000 depreciation = $25,000 The coinsurance clause here applies to the building limit; the stock is valued on ACV, and no coinsurance ratio is applied to it on these facts.
Combined.
- Building (after ratio and deductible): $229,375
- Stock: $25,000
- Deductible: already absorbed once in the building calculation; one occurrence, one deductible, applied to the total loss.
Total payable: $254,375.
What the shortfall cost. If the limit had been the recommended $1,280,000, the ratio would be 1.0 (or better), and the building payment would have been $300,000 − $5,000 = $295,000.
- Actual building recovery: $229,375
- Recovery at the adequate limit: $295,000
- Cost of the lower limit: $65,625 - roughly 22% of the building loss, on top of the deductible.
Frame this for the client correctly. Coinsurance is not a penalty the insurer invents at claim time; it is the mechanism that makes the insured a coinsurer of the gap between the limit purchased and the limit promised. The owner bought $1,000,000 of protection against a $1,600,000 exposure; the $65,625 is the portion of the risk he retained and is now funding himself.
3. The insured blames the agent. Evaluate the agency's position and what the file should have contained.
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What the agency has going for it. A signed acknowledgment rejecting the $1,280,000 limit is the single most valuable document in an E&O file. It shows the client was told what the adequate limit was and chose a lower one. It establishes comparative fault rather than unsupported agent error.
Why that is not the end of the analysis.
- Form of the acknowledgment matters. "Rejected higher limits" is weak. A document that shows the coinsurance math in dollars - "if you buy $1,000,000 and have a $300,000 loss, expect roughly $234,000 before deductible rather than $300,000" - is strong. Clients routinely win on the theory that they never understood the consequence, only the premium.
- Timing and who signed. Signed at binding, by an owner or officer with authority, is far better than signed later by a bookkeeper.
- Whether the recommendation was specific. "We recommend adequate limits" is not advice. A stated replacement cost figure with a stated coinsurance requirement is.
- Whether the deposit and renewal were re-checked. Replacement cost moves; a 2021 figure applied to a 2024 fire is a gap the agent may own.
Practical defense structure: the agent can argue the client made an informed economic choice and retained the risk. The client will argue the agent never explained the ratio in dollars. The signed document wins only if it demonstrates the explanation, not merely the rejection.
Improvement going forward: an agreed value option, inflation guard, or a stated-value approach should have been quoted alongside the coinsured program, with each option's cost and claim consequence shown in writing.