I'm not sure how you prove that you are partially disabled for any job that is primarily mental rather than physical. For example I once worked with a guy that was a lead software engineer. Shortly after he was hired, he got into a car accident and sustained a serious concussion. He claimed that after the concussion he could write basic code, but he didn't have the ability to concentrate enough to solve difficult problems or architect complex systems. How is an insurance company supposed to determine his level of disability? They don't really have a baseline to determine how strong of an engineer he was before the accident. Are they obligated to pay the difference between the salary of a junior and senior level engineer if he gets fired?