My neighbor is an elderly housewife who never worked (except under the table.) She was not disabled. She has been getting SSI since she was 65. She was never married. Her man left her. She has nothing. So she gets it.

"Supplemental Security Income (SSI) is a United States government program that provides stipends to low-income people who are either aged (65 or older), blind, or disabled." From: Supplemental Security Income - Wikipedia, the free encyclopedia

Notice the "either" and the "or." It's a good question.

For the purposes of this program, being over age 65 is the same as being disabled. You are considered too old to be expected to work. Makes sense when you think about it. SSI has kept a lot of elderly females off the streets. (though it's not just for them.) In a lot of states, if you get SSI, which is federal, the state also kicks in a few extra bucks on top of this. (Especially true in rich states.)

In most states, anyone who gets SSI automatically gets Medicaid.

In all states, anyone who gets SSI will get Medicare 2 years after their SSI payments start, or at age 65, whichever comes first.

Most people on SSI end up getting both Medicaid and Medicare.