The 80% rule in home insurance: How it works and why it matters (with examples)

The 80% rule in home insurance

The 80% rule in home insurance says that homeowners should insure their dwelling for at least 80% of its replacement cost in order for claims to be fully covered. If you don’t meet that threshold, your insurance company may reduce your claim payout — something the industry commonly refers to as a coinsurance penalty.

What is the 80% rule in home insurance?

According to the 80% rule in home insurance, your dwelling coverage limit — the part of a standard home insurance policy that helps pay to repair or rebuild the physical structure of your home — should equal at least 80% of your home's full rebuild cost, also called its replacement cost value (RCV).

If your dwelling coverage falls short of that 80% threshold, your insurer may apply a coinsurance penalty — meaning they'll only cover a portion of your loss, even for a covered claim.

This rule exists to make sure your home isn't left underinsured when you need your policy most. When a home is underinsured, homeowners risk being stuck with out-of-pocket costs that can total thousands of dollars — and insurers end up paying out more than what your premium payments were ever designed to support.

Calculating coverage needs with the 80% rule

Replacement cost value is simply what it would cost to rebuild your home today, based on current material and labor prices. It doesn’t factor in the purchase price of the home, the value of the land, or the home’s current market value, which is how much you could sell it for today.

A simple way to calculate the replacement cost value under the 80% rule is as follows:

(Home’s Square Footage x Local Construction Costs Per Square Foot) x 0.80

Pro tip: Keep in mind that the 80% rule represents a minimum coverage requirement, but it may not be enough to fully protect your finances against covered losses. Instead, consider insuring your home for 100% of its replacement cost.

How the 80% rule works (with examples)

Here are two examples of how the 80% rule works in home insurance. In both cases, the home’s replacement cost is $500,000, and the policy includes a $1,000 deductible.

Notably, most policies state the customer is either paid the amount after the coinsurance penalty, or the ACV of the loss, whichever is greater.

Why homeowners fall out of compliance

Just because your dwelling was initially insured for 80% of its replacement value doesn’t mean it stays that way. Several factors can cause your coverage limit to dip below the required 80% threshold over time. Some of the reasons might include:

• Inflation: Inflation can increase building material prices and labor costs, raising the replacement cost of your home.
• Home renovations: If you make any improvements to your home, like adding a new kitchen, it can increase the replacement cost.
• Building code changes: When local building codes change, it can make the cost of rebuilding your home more expensive.

How to stay protected and avoid penalties

The 80% home insurance rule protects insurance companies, but it also enables homeowners to receive full payment for insured losses, up to their policy limits. To avoid coinsurance penalties, it’s important to make sure that you’re fully covered. Here are some tips for staying protected:

• Review your home insurance policy annually: It’s a good idea to review your dwelling coverage limit before renewing your policy to make sure it’s still at least 80% of the current replacement cost value. If you're unsure what your home's RCV is, an insurance agent can help you calculate it. If you need more home insurance coverage, ask your insurer to increase your dwelling insurance limit.
• Notify your insurer about major renovations: If you’re planning any significant home improvements, it’s worth notifying your insurance company. Your insurer can recalculate the replacement value of your home and let you know whether you have enough home insurance coverage or need to raise your limits.
• Consider policy endorsements: Many home insurance companies offer endorsements, which are optional add-on coverage types that can provide more dwelling coverage. Examples include extended replacement cost coverage, an inflation guard rider, or ordinance or law coverage. It might be cheaper to add an endorsement than to raise your dwelling coverage limit.
• Ask a professional to estimate your rebuilding costs: While a simple formula can help you quickly estimate your home’s replacement value, it’s not exact. Consider having a professional appraiser provide a more accurate replacement cost value, or use an insurance tool that considers specific factors like the number of stories, exterior finishes, and foundation material.

Does the 80/20 rule apply to all coverages?

The 80/20 home insurance rule doesn’t apply to all coverages. Typically, it only applies to dwelling coverage (Coverage A). It never applies to personal liability coverage (Coverage E).

However, the 80% rule in home insurance can potentially impact your personal property coverage (Coverage C) and other structures coverage (Coverage B), since those coverage limits are typically tied to your dwelling coverage limit — usually set as a percentage of it.

If your home is underinsured and a coinsurance penalty applies, it can reduce the total amount available to cover a claim, which may indirectly affect how much you receive for other types of losses.

Frequently asked questions

What is the difference between the 80% rule and a deductible?

The 80/20 rule in home insurance impacts the percentage of an insured loss that your insurance company will cover. Your deductible is a fixed dollar amount or percentage-based amount that insurers subtract from your claim payout for a covered loss.

Is the 80% rule legally required?

The 80% rule isn't required by law, but coinsurance clauses are a standard feature of most home insurance policies. The specific threshold can vary by insurer — 80% is the most common, but some policies require you to insure your home for closer to 100% of its replacement cost value.

Does the 80% rule apply to a total loss?

The 80% rule tends to show up most in partial losses, but it can still affect what you receive after a total loss if your home was underinsured to begin with. Either way, your insurer will only pay up to your policy's coverage limit — so if rebuilding costs more than that limit, the difference comes out of your pocket unless you've added extra coverage like extended or guaranteed replacement cost.

Can I just insure my home for 100% replacement cost?

Yes, it’s typically recommended to insure your home for 100% of its replacement cost value. That way, you don’t risk being underinsured if you have a covered loss. But it’s still a good idea to review your policy annually to make sure you have enough coverage if the replacement value changes due to factors like inflation or a renovation.