The SSA defines “disability” as being unable to engage in substantial gainful activity because of a medically determinable physical or mental impairment or a combination of impairments expected to last for at least 12 continuous months or expected to cause death.
A child younger than 18 may qualify for disability benefits through the SSI program, provided they have a medically determinable physical or mental impairment or impairments that result in marked and severe functional limitations. The impairments must last or be expected to last for at least 12 months or be expected to cause death.