The Social Security Administration has defined disability as:
To meet our definition of disability, you must not be able to engage in substantial gainful activity (SGA) because of a medically determinable physical or mental impairment(s) that is either:
- Expected to result in death
- Has lasted or is expected to last for a continuous period of at least 12 months
There is a separate definition of disability for children (under age 18) who are applying for the Supplemental Security Income (SSI) program. A disabled child also qualifies for the SSI employment support described later in the Red Book.