Business interruption coinsurance explained with a step-by-step US example

What to take away

What coinsurance actually asks you to prove

Coinsurance is not a deductible and not a separate charge. It is a condition you agree to when you buy the policy. At claim time it asks one question: did you insure the business income value you were supposed to insure?

If the answer is yes, the loss is paid under the limit. If the answer is no, the insurer treats you as having bought only part of the coverage you needed. The payout shrinks by the same proportion.

This is why the clause matters most in a partial loss. A fire that closes one production line for six weeks is exactly the claim where the ratio gets applied. A total loss is capped by the limit anyway, so the penalty is less visible.

The requirement is stated as a percentage on the declarations page. Common choices are 50, 80, 90 and 100 percent. The percentage is not a discount you can shop for. It is the share of business income value you promise to carry.

State departments of insurance, from the California Department of Insurance to the Texas Department of Insurance, review the forms insurers file. The clause itself is standard, but the percentage and the valuation method are set by the policy you sign.

The National Association of Insurance Commissioners (NAIC) coordinates model rules across states, and the Insurance Information Institute (Triple-I) publishes consumer-facing explanations of business income coverage. Neither sets your limit. Your own numbers do.

Agents who hold the CPCU designation from The Institutes or belong to the Independent Insurance Agents & Brokers of America or the National Association of Professional Insurance Agents still have to collect the same figures from you. No association membership replaces the value worksheet.

The coinsurance formula written out, term by term

The coinsurance formula is written out as:

(limit of insurance carried / coinsurance requirement) x loss = claim payment

The coinsurance requirement is itself a product:

coinsurance percentage x business income value = coinsurance requirement

Four terms drive the result.

Limit of insurance carried is the business income limit shown on the declarations page. It is the most you can collect for that coverage part.

Coinsurance percentage is the share you agreed to insure, such as 80 percent. It appears on the declarations page or in the form.

Business income value is the amount of business income the policy should have covered during the period of restoration. It includes net profit, continuing fixed costs such as rent, and payroll for key employees if you insured it.

Loss is the covered business income and extra expense you actually sustained. The period of restoration is the time it reasonably takes to repair or replace the damaged property, plus a reasonable time to resume operations.

When the limit carried equals or exceeds the requirement, the ratio is 1.0 or higher and the loss is paid in full, subject to the limit. When the limit is lower, the ratio falls below 1.0 and the payment falls with it.

Some forms add a maximum penalty clause. That clause caps how far the ratio can drop, but it does not remove the penalty. Read the form, not the summary.

If you want to run the arithmetic on your own policy before a loss, the walkthrough in business interruption coinsurance formula uses the same terms.

A step-by-step US example with a partial loss

Use a mid-sized manufacturer in Ohio. The company has one plant, 60 employees and a steady order book. Its policy year runs January 1 to December 31.

Step 1. Set the business income value. The owner adds projected net profit of 900,000 dollars, continuing fixed costs of 500,000 dollars and insured payroll of 600,000 dollars. The business income value is 2,000,000 dollars.

Step 2. Read the coinsurance percentage. The declarations page shows 80 percent. The coinsurance requirement is 80 percent x 2,000,000 dollars, or 1,600,000 dollars.

Step 3. Read the limit carried. The owner bought a 1,200,000 dollar business income limit, because that matched a prior year's revenue estimate. The limit is 400,000 dollars below the requirement.

Step 4. The loss occurs. A sprinkler failure damages a packaging line in March. Repairs take ten weeks. The period of restoration runs ten weeks. Business income loss for the period is 300,000 dollars. Extra expense for temporary packaging is 50,000 dollars. Total covered loss is 350,000 dollars.

Step 5. Apply the formula. Limit carried divided by requirement is 1,200,000 / 1,600,000, or 0.75. The payment is 0.75 x 350,000 dollars, or 262,500 dollars.

Step 6. Compare to what full coverage would have paid. With a limit of 1,600,000 dollars or more, the same loss would have paid 350,000 dollars. The underinsurance penalty is 87,500 dollars.

The penalty is not the difference between the limit and the requirement. It is the shortfall created by the ratio, applied to the actual loss.

Step 7. Confirm the limit was not exhausted. The payment of 262,500 dollars sits below the 1,200,000 dollar limit, so the limit does not cap the result. The ratio does.

Step 8. Check the deductible. A 10,000 dollar business income deductible applies once, leaving 252,500 dollars. The deductible does not change the coinsurance ratio.

Step 9. Tax treatment. The premium paid for the policy is generally deductible as an ordinary business expense, and the claim proceeds are treated as income replacement under the rules in the Guide to business expense resources | Internal Revenue Service.

The owner should not net the proceeds against the lost revenue without checking with a tax adviser.

Step 10. Record the numbers. The owner files the value worksheet, the declarations page and the loss calculation together. That file is the same material a commercial property claim adjuster will ask for after a larger event.

What happens when the limit sits below the coinsurance requirement

The penalty is proportional, not flat. That is the part owners miss. A limit that is 25 percent short produces a 25 percent cut on every partial loss, no matter how small the loss.

In the Ohio example the ratio was 0.75. Every covered dollar of business income and extra expense paid 75 cents. The owner absorbed 25 cents of each dollar.

Several smaller claims hurt more than one large claim under this rule. Three separate 100,000 dollar losses in one policy year would each pay 75,000 dollars, for a total penalty of 75,000 dollars. The limit itself would still have room.

The penalty also interacts with the period of restoration. A longer shutdown produces a larger loss, so the same ratio produces a larger dollar penalty. Repair delays, permit delays and equipment lead times all extend the period and increase the exposure.

Extra expense is not immune. If the policy includes extra expense inside the same limit, the ratio applies to that spending too. Renting temporary space or paying overtime to catch up all gets scaled by the same fraction.

Insurers apply the clause at settlement. The adjuster computes the requirement from the values you submitted, then applies the ratio. Disputes usually turn on the business income value, not on the percentage.

If the penalty leaves a gap, two federal backstops exist. FEMA business assistance can help with certain disaster-related needs through Businesses | FEMA.gov. Separately, the Small Business Administration offers low-interest disaster loans described at SBA disaster assistance: Low-interest relief loans - Small Business Administration.

Neither is a substitute for adequate coverage, and both have eligibility rules.

Choosing a limit: gross profit, business income and extra expense

The limit should come from a value worksheet, not from a revenue line. Three figures feed it.

Gross profit is the starting point in many forms. It is net sales less the cost of goods sold, plus other earnings from the business. It captures the income the business would have earned had the loss not happened.

Business income is the coverage itself. It pays the net profit you would have earned plus continuing normal operating expenses, including payroll for employees who are not laid off. Payroll treatment is a choice you make when the policy is written.

Extra expense pays costs above normal operations to avoid or shorten a shutdown. Temporary location, expedited shipping and extra advertising are typical items. Some policies combine the two into one limit, and some split them.

A combined limit is simpler but riskier. A long shutdown can drain the shared limit with extra expense before business income is fully paid. A split limit costs more but protects each bucket.

Ordinary payroll is the largest swing item. Including it raises the limit and the premium. Excluding it lowers both, but you must be able to lay people off without damaging the business.

Use a 12-month projection, not a trailing 12-month actual. The policy responds to the future you would have had, not the past you already booked. Growth and new contracts belong in the number.

For the broader relationship between values, perils and payout, see commercial property coverage. The limit selection logic is the same whether the property is a plant, a restaurant or a medical office.

A common error is insuring to the loan value or the building value. Business income is separate from the building and contents limits. Mixing them produces a limit that looks adequate and is not.

The worksheet should be signed and dated. It is the document that shows the requirement was calculated in good faith if a claim is questioned.

Where coinsurance appears outside business interruption forms

Coinsurance is not unique to business income. The same structure appears in several commercial property forms, and the same arithmetic applies.

Building and contents coverage often carries an 80 or 90 percent coinsurance clause tied to replacement cost. If the building limit is below that share of replacement cost, every partial loss is scaled down.

Blanket limits apply one limit across several locations. The coinsurance test is applied to the combined values, which can help when locations have uneven exposure. It can also hide a shortfall if one location carries most of the value.

Agreed value endorsements suspend the coinsurance clause for the policy term. The insurer accepts the values you submitted, usually after reviewing a statement of values. The trade-off is that you must update the values at each renewal.

Reporting forms work differently. You deposit a premium and report values monthly or quarterly, and the premium is adjusted at audit. A reporting form can reduce the coinsurance risk if reports are accurate and on time.

Commercial flood coverage through the National Flood Insurance Program uses its own limits and rules, and coinsurance does not apply the same way. Do not assume the property coinsurance clause carries over.

Workers' compensation is a separate line with state rating bureaus such as NCCI in many states. It has its own premium audit rules, not a coinsurance ratio.

The details that trip people up are collected in commercial property requirements. Most of them are valuation issues, not coverage issues.

Reviewing your limit before the next renewal

Renewal is the natural checkpoint. Values change during the year, and the limit on the expiring policy reflects the values you gave the insurer the last time.

Start 90 days before the renewal date. That leaves time to gather figures, get quotes and make a decision without pressure.

Run this routine:

If the gap is large, fix it in stages. Raising the limit at renewal is cheaper than discovering the gap after a loss. A mid-term endorsement can close part of the gap if the insurer agrees.

Do not lower the limit to cut premium without rerunning the requirement. A lower limit can drop you below the coinsurance threshold and cost more at claim time than the premium saved.

The mistakes that create these gaps are usually administrative. They are described in commercial property mistakes, and most are avoidable with a calendar reminder and a current worksheet.

Common questions