A number of states pay supplements to the basic federal SSI amount. In these states, the supplement is added directly onto the federal SSI payment. This means that the applicant need apply only once – to Social Security – to receive both the basic amount and the supplement. Both amounts are included in one payment, which is administered by the SSA. The supplement amount differs for a single individual, a couple, or a person who is blind. The amount may also differ if the person lives in the household of someone else, in group living arrangements, or in a nursing facility. States in which the supplement is federally administered include California, Delaware, District of Columbia, Hawaii, Iowa, Massachusetts, Michigan, Montana, Nevada, New Jersey, New York, Pennsylvania, Rhode Island, Utah, and Vermont. (In several of these locations, the individual State administers the supplement for people living in certain residential settings, while the SSA administers the supplement for other residential arrangements.)

Most other states also provide some kind of supplement to the basic federal SSI payment, but the types of supplements and rules for qualifying are administered solely by those states. These supplements must be applied for separately, at the social welfare agency of the applicant's county of residence.