* If the child is age 18 or older as of the application date, the child will be deemed to be disabled on the basis of a written certificate from one or more licensed and practicing physicians stating that the child is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or can be expected to last for a continuous period of not less than 12 months. The physician's determination of disability shall be determined in accordance with 20 CFR 416.905 through 416.911.
* If the child is under age 18 as of the application date, the child will be deemed to be disabled on the basis of a written certificate from one or more licensed and practicing physicians stating that the child has a medically determinable physical or mental impairment or combination of impairments that causes marked and severe functional limitations, and that can be expected to cause death or that has lasted or can be expected to last for a continuous period of not less than 12 months. The physician's determination of disability shall be determined in accordance with 20 CFR 416.905 through 416.911.
Ill. Admin. Code tit. 80, § 1600.461