Here is a part of a great article from Nolo Press and Disability Secrets about the intricacies of the disability program for kids:
“Children can qualify for disability benefits only through the Supplemental Security Income (SSI) program. Social Security Disability Insurance (SSDI) is available only to disabled people who have worked a certain length of time in jobs that have paid Social Security taxes. A child, even if 17 or 18, cannot have worked long enough to be insured under SSDI. (However, if a child’s parent is disabled and collects SSDI, the child may be able to receive dependents’ benefits. And after turning 18, a disabled teen could continue to receive SSDI benefits as a “disabled adult child.”)
When awarding Supplemental Security Income (SSI) benefits to children, the Social Security Administration (SSA) accounts for the fact that diseases and impairments can have very different effects on children and adults.
“SSI is for individuals with low income who have become disabled; there is an income and resource limit for children to qualify for this benefit. The income and resources of the child are considered, as well as the income and resources of the family members that the child lives with. For example, a disabled infant who lives at home with their parents may be barred from collecting SSI even if the infant has no income, if their parents make above a certain amount of money. (For information on the income and asset limits, see our section on financial eligibility for SSI.)
“Even a child (anyone under 18) who does not live at home may still have the income and resources of their family members considered if they go home periodically and are under the care of those family members when at home.”