What an Impairment Rating Tells You
An impairment rating is a doctor's estimate of how permanently a workplace injury has reduced your physical or mental function. It is the number that drives the lump-sum payment you may receive after settling a workers' compensation claim. The rating does not measure your lost wages or your ability to return to work; it measures the lasting loss of a body part or system compared to a healthy, uninjured state.
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Most jurisdictions follow the American Medical Association's Guides to the Evaluation of Permanent Impairment, commonly called the AMA Guides. Some states still use older versions or their own state-specific schedules, so the exact method can vary by where the injury occurred. Regardless of the manual, the process follows a predictable path.
How the Impairment Rating Process Works
You typically receive a rating only after you have reached maximum medical improvement, or MMI. MMI means your condition has plateaued and further treatment is unlikely to produce meaningful improvement. At that point, the treating physician or an independent medical examiner examines you, reviews diagnostic studies, and applies the rating methodology to each affected body part.
The evaluation includes measurements of range of motion, muscle strength, sensory loss, and functional limitations. For mental health claims, the rating may assess cognitive deficits, emotional regulation, or the ability to maintain interpersonal relationships. The physician then converts the clinical findings into a percentage, with higher percentages representing greater permanent loss.
What the Rating Percentage Means
A rating of zero means the injury has left no measurable permanent impairment. A rating of one percent indicates a very slight loss of function, while a rating of 100 percent for a specific body part represents a total loss. For whole-person impairment, which combines multiple body parts into a single number, the scale works the same way but the financial impact is much larger.
The Schedule of Ratings and Payouts
Most states assign a dollar value to each percentage of impairment, often based on a portion of the employee's average weekly wage. The table below shows a simplified view of how a typical schedule applies to common injuries.
| Body Part | Example Rating | Typical Weeks Allowed | Context |
|---|---|---|---|
| Arm | 10% | 200 weeks | Fracture with residual weakness |
| Leg | 5% | 150 weeks | Joint replacement, mild limp |
| Lower Back | 15% | 300 weeks | Disc injury with chronic pain |
| Hand | 20% | 150 weeks | Crush injury, reduced grip |
| Eye | 30% | 150 weeks | Partial vision loss |
The number of weeks allowed varies by state and by the specific body part. The payout is usually the number of weeks multiplied by the state's assigned dollar rate per week, then multiplied by the impairment percentage. Some states also include a base amount for the injury itself, separate from the impairment calculation.
Impairment vs. Disability
One of the most common points of confusion is the difference between impairment and disability. Impairment is a medical concept: it is what the doctor's examination shows. Disability is a vocational concept: it is what you can no longer do in the work world. A person can have a 10% impairment rating but be completely disabled from their previous job, or they can have a 30% impairment rating and still work full-time in a modified capacity.
Your impairment rating affects only the permanent partial disability payment. Wage loss benefits and retraining costs are handled separately and depend on your actual earning capacity after the injury.
Disputing an Impairment Rating
If you believe the rating is too low, you have options. Most systems allow you to request an independent medical examination, or IME, paid for by the insurance carrier. You can also present your own medical evidence, including treating physician reports and functional capacity evaluations. In some states, you may appeal to a workers' compensation board or hearing officer who will review the medical records and testimony before issuing a decision.
Because the rating directly controls the size of your settlement, it is worth documenting every limitation in your daily life and keeping records of the activities you can no longer perform. The more specific the evidence, the stronger your challenge to a low rating.
When to Consult a Workers' Compensation Attorney
You should consider legal advice if your rating seems low compared to your symptoms, if the insurance company offers a settlement that does not match the rating, or if you have multiple body parts rated separately and want them combined correctly. An attorney can also help if you have a pre-existing condition that the insurer is using to reduce your rating. Many workers' comp lawyers offer free case reviews and only collect a fee if they recover additional benefits for you.