Supplement Security Income is an important program in the United States. It helps disabled adults, disabled children and certain seniors meet their financial needs. However, the program is not open to everyone and requires an extensive application in order to be approved. As part of this application, people need a series of documents in order to be approved. Without the right documentation, the Social Security Administration may deny a person's SSI application.
According to the Social Security Administration, a person needs a social security number -- or card -- in order to apply for SSI benefits. If a person does not have a social security number, then the person will need to apply for one before applying for SSI benefits.