Supplemental Security Income, or SSI, is a federal benefit program managed by the Social Security Administration (SSA). In most states, there is an additional or supplemental benefit program for disabled children.
Currently, only Arizona, North Dakota, Mississippi, and West Virginia lack a state supplement to SSI for children. In all other states, and the District of Columbia, there is some form of state supplement, though not all state benefits are managed and administered in the same way.
In some cases, the state is entirely responsible for State SSI Supplements. In others, the SSA manages and pays state-level benefits. There are also states in which the SSA and the state share responsibility for supplemental, state-level benefits. The SSA maintains an up-to-date list (link - http://www.socialsecurity.gov/ssi/text-benefits-ussi.htm) of which states fall into each of these categories. Knowing which entity is responsible for administration of state-level SSI supplements is essential when questions arise regarding benefits.
In addition to state disability benefits, disabled children are often eligible for other forms of assistance administered at the state level, including Temporary Assistance for Needy Families (TANF), the Supplemental Nutritional Assistance Program (SNAP), and Medicaid, among others.