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The Coinsurance Penalty: How Underinsuring Your Buildout Backfires

By Richard Sweet. Reviewed by Richard Sweet. Updated July 7, 2026.

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Coinsurance is the clause that punishes you for insuring your restaurant buildout on the cheap, and it does its worst damage on the partial losses that actually happen. If you insure your property below the percentage of value your policy requires, the carrier can reduce your claim payment in proportion. You do not have to burn down to get hurt by it. Here is how it works and how to switch it off.

What the clause requires

A coinsurance clause asks you to insure your property to a stated percentage of its value, commonly 80, 90, or 100 percent. In exchange for that promise, the carrier prices the coverage on the assumption that you carried your share. If a loss occurs and you insured for less than the required amount, the coinsurance provision reduces your recovery. The logic is that an owner who insures to half of value and pays for half the exposure should not collect as if they insured to full value. Fair or not, it is in the policy, and it applies quietly until a claim triggers it.

The formula in plain language

The math is simpler than it sounds. Take the amount of insurance you actually carried, divide it by the amount you should have carried under the coinsurance requirement, and multiply that fraction by the loss. Subtract your deductible, and that is your recovery. If you carried three-quarters of what you should have, you recover roughly three-quarters of a covered partial loss. The clause does not care that you had a real, covered fire. It cares about the ratio between what you insured and what you should have. That ratio becomes the haircut on your check.

A worked example

Round numbers, illustrative only, to show the formula and not as a price or a quote. Say your tenant buildout would cost 500,000 to replace. Your policy carries an 80 percent coinsurance clause, so you should insure it for at least 400,000. Instead you insured it for 300,000. A partial fire causes a 100,000 loss. The carrier runs the formula: 300,000 divided by 400,000 equals 0.75. Your 100,000 loss is paid at 75 percent, so 75,000 before the deductible, and you absorb the remaining 25,000 plus your deductible. Nothing about the fire was denied. The underinsurance alone cost you a quarter of the claim.

Why tenant improvements are the trap

The most undervalued number on a restaurant policy is the buildout. Tenant improvements and betterments, the kitchen, hood, finishes, plumbing, and electrical you installed in a leased space, are expensive to replace and easy to insure for too little. Owners tend to insure what they recall spending, sometimes years ago, rather than what it would cost to rebuild today. Add rising construction and equipment costs, and a figure that was reasonable at signing drifts below replacement value on its own. The clause then does the rest. This is why a buildout, a renovation, or simple time is a reason to recheck the insured value.

Agreed value as the fix

The clean fix is to insure to value and keep the number current. The stronger fix, where available, is agreed value. Agreed value is an option that suspends the coinsurance clause when you and the carrier agree on the insured value up front, usually backed by a statement of values. When it applies, the proportional penalty does not, so a partial loss is not reduced by a valuation argument at claim time. You still need the value to be realistic, but you remove the trap. For a restaurant with a significant buildout, insuring to replacement value and asking about agreed value are two of the highest-value decisions on the policy.

Questions to ask your advisor

  • What coinsurance percentage does my property policy require?
  • How were my tenant improvements valued, and is that number current?
  • Does my insured value reflect today’s replacement cost, not what I spent years ago?
  • Is agreed value available on my policy, and would it suit my situation?
  • If I had a partial loss tomorrow, would a coinsurance penalty apply?
  • Should I update my statement of values after recent construction or price increases?

The penalty is avoidable, but only before the loss. Once the claim is filed, the ratio is already set.

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What many people don't realize

The part that catches owners off guard

  • Coinsurance requires you to insure to a set percentage of value.
  • Underinsuring can cut your claim payment proportionally.
  • Tenant improvements are easy to undervalue.
  • Agreed value can remove the penalty when it applies.
The Vantage Point

What we see most often

Coinsurance is the clause that turns a good claim into a short one. You do not have to lose everything to

feel it. Underinsure your buildout, have a partial loss, and the carrier can pay a fraction of it because

you carried a fraction of the value.

The fix is not exotic. It is insuring your tenant improvements to value and, where available, using

agreed value to switch the penalty off. Both are decisions you make before a loss.

A real example

Consider a composite example, illustrative only, using round numbers to show the math and not as a price

or a quote. A tenant's buildout would cost 500,000 to replace. The policy has an 80 percent coinsurance

clause, so the owner should insure at least 400,000. The owner insured for 300,000. A partial fire causes

a 100,000 loss. The carrier applies the coinsurance formula: 300,000 divided by 400,000 is 0.75, so the

claim is paid at 75 percent, 75,000 before the deductible, and the owner absorbs the rest. The building

did not burn down, but the underinsurance still cost real money.

Details changed to protect privacy. Shared to illustrate, not to promise an outcome.

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When to review

It may be time for a coverage review if:

  • You completed or inherited a significant tenant buildout
  • You are unsure how your tenant improvements were valued
  • Construction and equipment costs have risen since you bound coverage
  • Your policy has a coinsurance clause and no agreed value
  • You have never checked your insured value against replacement cost
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Frequently asked

Frequently asked

What is a coinsurance penalty?
It is a reduction in your claim payment that applies when you insured your property below a required percentage of its value. The carrier pays only the proportion of the loss that your coverage bears to the amount you should have carried, subject to policy terms.
How does the coinsurance formula work?
In plain terms: the amount of insurance you carried, divided by the amount you should have carried, times the loss, minus your deductible. If you carried three-quarters of what you should have, you recover about three-quarters of a covered partial loss.
Does coinsurance only matter in a total loss?
No, and that surprises owners. In a total loss you simply hit your limit. The penalty bites hardest on partial losses, which are far more common, because that is where the proportion math reduces an otherwise full payment.
Why are tenant improvements so easy to undervalue?
Because owners insure what they remember spending, not what it would cost to rebuild today. Buildouts, kitchens, and finishes are expensive to replace, and construction costs rise. An old or casual number quietly drifts below replacement value.
What is agreed value?
Agreed value is an option that suspends the coinsurance clause when you and the carrier agree on the insured value up front, usually supported by a statement of values. When it applies, the penalty does not, though you should confirm the terms.
How do I avoid the penalty?
Insure your tenant improvements and property to replacement value, keep the figure current as costs rise, and use agreed value where it is available. A coverage review checks your insured value against a realistic replacement cost.
RS
Written and reviewed by

Richard Sweet

Founder and Principal Advisor, Vantage Point Risk

Richard Sweet runs Vantage Point Risk, an independent insurance and risk advisory for property owners, real estate investors, business owners, and families. He works with investors every week on the coverage decisions that decide how a claim actually turns out, and writes the Learning Center to put those decisions in plain language.

Reviewed for accuracy by Richard Sweet. Last updated July 7, 2026.

Richard also writes The Vantage Point, notes on building a better business.

This article is general information, not insurance advice, and the numbers in the example are illustrative to show the formula, not a price or a quote. Coinsurance clauses, valuation, and agreed value vary by policy form and carrier. For your restaurant, verify the specifics with a licensed advisor.

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