Coinsurance clause explained with examples
A coinsurance clause reduces a property claim payment when the policy limit is lower than a set percentage of the property's value, commonly 80%. The payment is the limit carried divided by the limit required, times the loss, minus the deductible. The unpaid part is often called a coinsurance penalty. The policy wording controls the actual calculation.
What a coinsurance clause does
Coinsurance rewards insuring to value. The policy names a percentage, often 80%, and requires a limit at least that share of the property's value on the date of loss. If the limit meets the requirement, covered losses are paid up to the limit, less the deductible. If it falls short, the insurer pays only a proportion of the loss. The shortfall becomes the insured's share. The term describes a condition in the policy, not a separate coverage.
The formula: did over should, times the loss
Use four inputs: the limit carried (did), the value on the date of loss times the coinsurance percentage (should), the covered loss and the deductible. The working formula is did divided by should, times the loss, minus the deductible, capped at the limit. If did is equal to or greater than should, the ratio is treated as 1 and no penalty applies. Check the order of operations in the actual form; some forms apply the deductible differently.
Original example 1: underinsured building
A fictional commercial building is worth $500,000 on the date of loss. The policy has an 80% coinsurance clause, a $300,000 limit and a $2,000 deductible. The covered loss is $80,000. The required limit is 80% of $500,000, or $400,000. The ratio is $300,000 divided by $400,000, or 0.75. Then 0.75 times $80,000 is $60,000, and subtracting the $2,000 deductible leaves $58,000. The insured carries $22,000 of the loss: the $20,000 penalty plus the deductible.
Original example 2: insured to value
Keep the same fictional building and loss, but raise the limit to $420,000. The required limit is still $400,000. Because $420,000 meets the requirement, the ratio is 1. The payment is the $80,000 loss less the $2,000 deductible, or $78,000. The only difference between the two examples is the limit carried, yet the payment changes by $20,000. That is why the value used for the requirement, and its date, matter so much in a coinsurance dispute.
How coinsurance interacts with ACV and RCV
The value in the should calculation follows the policy's valuation basis. On an actual cash value form, the requirement is usually measured against actual cash value; on a replacement cost form, against replacement cost. Homeowners forms often use a similar test for dwelling replacement cost: if the dwelling limit is at least 80% of full replacement cost, the loss is paid at replacement cost, and if not, the insurer pays the greater of actual cash value or a proportional amount. Read the loss settlement section to see which test applies.
Agreed value and other ways around the penalty
Some commercial property policies offer an agreed value option that suspends the coinsurance condition for a stated period when the insured and insurer agree on the value in advance. Other policies use a coinsurance waiver for small losses or no coinsurance clause at all. Each depends on the policy and endorsement wording. Update the agreed value before it expires and keep the valuation records used to set it.
Working checklist
- Find the coinsurance percentage and valuation basis
- Document the value on the date of loss
- Compare the limit carried with the limit required
- Apply the deductible in the order the form states
- Check for agreed value, waivers or endorsements
Sources and further reading
These references provide background. The workflows and fictional exercises above are original learning examples. State-specific sources are labeled and should not be applied as nationwide rules.
- IRMI: coinsurance definition
- Texas Department of Insurance: homeowners insurance guide (80% replacement cost requirement)
- NAIC: glossary of insurance terms
General education, not an assessment of an individual claim or legal advice. Verify current policy provisions and state requirements. No particular payment or dispute outcome is promised.