Defining a Coinsurance Formula

What Is the Formula for Coinsurance?

The coinsurance formula is a homeowner's insurance calculation that determines how much money a homeowner would get back after a claim. When a homeowner fails to maintain coverage of at least 80% of the home's replacement value, the coinsurance formula kicks in. Those who file a claim in this case will only receive a partial reimbursement based on the formula.

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KEY TAKEAWAYS: 

• The coinsurance formula determines how much a homeowner or property owner will be reimbursed when a claim is filed.
• When a property owner fails to maintain coverage of at least 80% of the home's replacement value, the coinsurance formula is used.
• When a property owner insures for less than the coinsurance clause requires, they are essentially opting to keep a portion of the risk.
• In this instance, the owner becomes a "co-insurer" and, according to the coinsurance calculation, will share any loss with the insurance company.

The Coinsurance Formula in Action

The coinsurance formula is straightforward. Divide the amount of coverage on the house that was actually carried by the amount that should have been carried (80 percent of the replacement value). The amount of the refund will be determined by multiplying this amount by the amount of the loss. A secondary coinsurer will provide the leftover cash if the reimbursement value exceeds the stipulated limits of a single insurance company.

Coinsurance is a clause that insurance firms employ in insurance contracts for property insurance policies like buildings. This provision ensures that policyholders insure their property for a reasonable amount, and that the insurer obtains a reasonable premium for the risk. In most cases, coinsurance is given as a percentage. Most coinsurance clauses require policyholders to insure a property's actual worth to 80, 90, or 100 percent. For example, a structure with a replacement value of $1,000,000 and a coinsurance provision of 90% must be insured for at least $900,000. With an 80 percent coinsurance clause, the identical building must be insured for at least $800,000.

The Coinsurance Formula in Practice

When a property owner insures for less than the coinsurance clause requires, they are essentially opting to keep a portion of the risk. As a result, they become a "co-insurer" and, according to the coinsurance formula, will share the loss with the insurance company.

The following are two examples of how the coinsurance clause works:

$1,000,000 in building value

Coinsurance is required in 90% of cases.

$900,000 in insurance coverage is required.

Actual Insurance Amount $600,000

Loss amount: $300,000

(Actual Amount of Insurance ) X Amount of Loss = Amount of Claim is the coinsurance formula (Required Amount of Insurance)

When you plug in the numbers above into the formula, you get the following result:

($600,000) $300,000 multiplied by ten equals $200,000 ($900,000).

As a result, because the owner maintained one-third of the risk rather than transferring it to the insurer, the owner must pay a $100,000 coinsurance penalty. As a result, the owner bears a portion of the loss. The coinsurance calculation would look like this if the building had been insured to the level required by the coinsurance clause (in this example, 90%).

Amount of Claim = (Actual Amount of Insurance) X Amount of Loss (Required Amount of Insurance)

($900,000) X $300,000 = $300,000 ($900,000) X $300,000 X $300,000 X $300,000 X $300,000 X $300,000

In the second scenario, the owner is not a co-insurer because they completed the coinsurance requirement, and the claim is paid without penalty.

Business interruption policies also have coinsurance clauses. These clauses ensure that policyholders adequately insure their revenue stream.