Coinsurance Penalties: When Being Underinsured Costs You Extra

Coinsurance is a provision in some insurance policies — particularly commercial policies — that penalizes you if your coverage limits are too low relative to the value of your property. If a coinsurance penalty applies, you won't receive full payment even for a covered loss.

How the Coinsurance Penalty Works

A typical coinsurance clause requires you to insure your property for at least 80% of its replacement cost. If you don't, the penalty kicks in proportionally. The formula is: (Amount of Insurance Carried ÷ Amount Required) × Loss = Payment.

For example, if your building is worth $1,000,000, the 80% coinsurance requirement is $800,000. If you only carry $600,000 in coverage and have a $200,000 loss, you'd receive: ($600,000 ÷ $800,000) × $200,000 = $150,000 — a $50,000 penalty for being underinsured.

Total Losses and Coinsurance

Here's something important that even some adjusters get wrong: if the property is a true total loss, there is no coinsurance penalty. It's simply how the math works. If the loss equals or exceeds the coverage limit, the formula always produces the full policy limit — the penalty disappears.

I've seen carriers order real estate appraisals on total-loss commercial properties specifically to check for coinsurance penalties. This is a waste of time and money — if it's truly a total loss, the math makes the penalty irrelevant.