Experience Rating Overview

The Experience Rating Plan tailors, or modifies, the price of insurance and provides an incentive for safety.

The Experience Rating Plan modifies or adjusts an employer’s premium based on past loss experience. The concept is simple: a good claims history results in lower premiums, while a poor claims history results in higher premiums.  The program tailors the price of insurance and provides an incentive for employers to invest in safety.

Differences Among Employers

All states classify employers into categories for workers compensation insurance. Each classification has its own advisory rate. So, within a state, the same advisory rate applies to all employers who fall into a given class. For example, all jewelry stores in Indiana are grouped together under code 8013 and all machine shops are under code 3632. The advisory rate applied in each class is an average rate, and does not recognize any individual characteristics of that employer.

The Experience Rating Plan recognizes differences within the same business classification. The classification system subdivides employers according to product, process, operation, kind and character of business. Experience rating recognizes that employers can differ in a variety of ways with regard to safety.  This includes the degree of automation, PPE requirements, training, and the implementation and enforcement of safety programs. These factors will all affect the chance for an injury to occur. The Experience Rating Plan provides a measurable way to reflect these factors.


The Experience Rating Plan is mandatory in Indiana. To be eligible for experience rating, an Indiana employer must reach $3,250 in average annual subject premium or $6,500 in one year for policies in the experience period. Refer to the Experience Rating Plan Manual Rule 2-A, page R4. 

The January 1, 2023 advisory rate filing updated the amounts. As of 07/01/23, the eligibility amounts increase to $3,250 average or $6,500 in one year. Here’s a table summarizing recent changes:  

DateAverage annual subject premiumOne Year in experience period
Prior to 07/01/18$2,500$5,000


As of 7/1/2024





Item Filing E-1404, establishes a methodology to establish eligibility levels annually as part of the January 1 rate filing.  The premium eligibility amounts are intended to be high enough so that at least one claim is expected in the three-year period used in experience rating.  

Also refer to the “Algorithm for Premium” document for a detailed listing of premium categories. 

Eligibility is based on premium (prior to experience rating, premium discount or schedule rating). The $6,500 eligibility is not the premium on the current policy. It is for any one year in the experience period.

Experience Period

The Plan basically uses three years of an employer’s past policy experience (payroll and losses). For instance, an experience rating effective 01/01/2024 would normally contain these policy years:

  • 01/01/2022
  • 01/01/2021
  • 01/01/2020

For more information, check out the Experience Period document.


The Plan uses a formula to arrive at a bottom line factor (mod) that is multiplied by the class code premium which “modifies” the premium. A factor of 1.10 means the employer pays an additional 10% in premium. A factor of 0.90 means the employer pays 10% less in premium.

Expected vs Actual

The experience rating formula compares actual losses against expected losses. Expected losses are calculated based on the employer’s classification codes and size of payroll. If an employer’s actual losses are better than expected, then it earns a discount or credit on its premium (mod factor less than 1.00). Conversely, if an employer’s actual losses are worse than expected, then it earns a surcharge or debit on its premium (mod factor greater than 1.00).

Open Claim

Reserve amounts for open claims are treated as actual losses, so reserves directly impact the modification factor. If claims are still open for any of these years, then the carrier estimates the ultimate cost of the claim (reserve) and reports that amount to us, with updates once a year. An important point to notice is that a claim that is four years old could still affect the current rating.