Unlike other disability benefit programs, Social Security disability, a program that is administered by the social security administration, compensates individuals who are totally disabled not partially disabled. Social Security disability benefits are paid to individuals who are determined to be unable to engage in any kind of substantial gainful work activity because of a medically determinable mental and/or physical impairment, or a combination of either types of impairments.
When making a Social Security disability decision, disability examiners–the individuals who actually process SSD and SSI claims at state-level disability determination services for the social security administration–must gather information from the medical sources provided by the individual claimant at their initial disability interview. If the medical, and sometimes school, records gathered by an examiner are insufficient to make a disability determination, SSA will pay for an individual to attend something known as a CE or consultative examination. Consultative exams are performed by independent doctors who have agreed to conduct them in exchange for compensation. The purpose of consultative examinations is to ascertain A) if the individual does indeed have a medically determinable impairment and B) the severity of the impairment (s).
In the social security disability and SSI disability system there is no concept of partial disability, so disability examiners must use the available information gained from medical record documentation and, if applicable, consultative examinations, as well as information about an individual's past substantial and gainful work activity to determine if their functional capacity (what they are able to do despite their limitations) is so restrictive that it precludes all other types of substantial gainful work activity they may have performed in the past 15 year period, as well as any other type of work performed in the general economy.
Most federal disability decisions are a complex blend of medical and vocational factors that will either support the fact that the individual's condition is totally disabling, or not. If there is a possibility that an individual is able to perform substantial work activity with the limitations imposed upon them by their medical or mental condition, their disability claim will be denied.
The SSA definition of disability clearly states that an individual must have been unable to perform substantial work activity for twelve months; or they expect to be unable to perform substantial work activity for twelve months; or their condition is expected to result in death due to a medically determinable mental or physical impairment. So as you can see, the definition of disability for Social Security does not allow for partial disability compensation, just as it does not provide for temporary disability benefits, or percentage-of-disability benefits.