Impairment Ratings Explained — How They Affect Your Settlement

An impairment rating is a medical assessment of the percentage of permanent functional loss caused by your work injury. It is expressed as a percentage of whole person impairment (WPI) or, for scheduled injuries, as a percentage of the affected body part.

The rating is assigned by a physician using standardized guides, most commonly the AMA Guides to the Evaluation of Permanent Impairment. The edition used varies by state — California uses its own PDRS, most states use the 5th or 6th Edition of the AMA Guides, and Colorado uses the 3rd Edition (Revised).

The impairment rating is the primary driver of permanent partial disability (PPD) benefit calculations. A higher rating produces higher benefits.

Under the AMA Guides system used in most states, a 10% WPI might produce 40–80 weeks of PPD benefits, depending on the state multiplier. In scheduled injury states like New York, the rating is multiplied by the fixed number of weeks assigned to that body part (e.g., 288 weeks for a leg, 312 weeks for an arm). In California, the PDRS converts the rating to a specific number of PD weeks at a fixed weekly rate.

Insurance carriers frequently use IME physicians who assign lower ratings than treating physicians. You have the right to challenge the IME rating with your own medical evidence. In California, the QME or PQME process provides a neutral third-party physician evaluation. In most other states, a hearing officer weighs the competing medical opinions based on the physicians' reasoning, qualifications, and consistency with objective medical findings.