Enhance the precision of your homeowners rating with by-peril analysis

With the new Homeowners By-Peril Rating Supplement, you’ll now be able to evaluate the perils that pose the greatest risk for policies in your homeowners book of business and rate the exposure more accurately.

The Homeowners By-Peril Rating Supplement is an alternate rating plan designed for your use as an optional supplement to the standard ISO Homeowners Rating Manual classification and rating system. The new product is available to participating ISO Homeowners customers at no additional charge and is delivered through ISOnet.

The benefits of by-peril analysis

Traditional rating for homeowners polices considers perils on a combined, all-perils basis — an approach that doesn’t specify what portion of the rate is attributable to each peril. With by-peril rating, separate loss costs developed for each peril allow you to analyze the portion of the total loss cost attributable to each peril and look at the effects of perils individually.

ISO derived the Homeowners By-Peril Rating Supplement from some of the models of ISO Risk Analyzer® Homeowners. The supplement provides an alternative way to develop a loss cost. The rating rules start with territory-level, peril-specific loss costs at the base risk level. Then rules apply peril-specific rating relativities, such as amount of insurance and deductible, to the by-peril loss costs separately for:

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  • fire
  • lightning
  • water (non-weather related)
  • water (weather related)
  • wind (excluding hurricane
  • hail
  • theft and vandalism
  • all other perils (excluding hurricane and earthquake)
  • liability (including medical payments)
  • hurricane

With the new by-peril rating supplement, you get base advisory prospective loss costs, rating factors, and additional rating information for the individual perils. You can develop an all-peril loss cost by adding all the by-peril loss costs together.

Being able to look at the effects of perils individually and understand what part of the total combined loss cost is attributable to each peril will help you better evaluate your book of business and improve your rating accuracy.

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Adopting the optional rating tool

You can adopt the alternate rating plan as you see fit, implementing it on your own timeline and establishing your own effective date.


Throughout 2013, ISO will be filing the Homeowners By-Peril Rating Supplement as an enhancement to our homeowners rating information. ISO is not filing on behalf of participating insurers.

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