There are Two Types of Disability Programs.
If you have limited lifetime earnings AND have very limited assets the program called Supplemental Security Income, “SSI.” Title XVI of the Social Security Act (20 C.F.R.. §416 et. seq.)
SUPPLEMENTAL SECURITY INCOME; also known as SSI; also known as Title XVI
When people think of the phrase “Social Security” and the word “disability” at the same time, they usually come up with the acronym SSI. The two programs are similar in that they both are about the inability to work due to physical/mental conditions. But they are way different in how they are funded and the purposes are different. For one thing, people age 65 and over who are not insured for Retirement benefits; because they did not have 40 quarters of credit over their lifetime, qualify for SSI. Other people use SSI is because their disability benefits (from SSDI) are less than about $1,000 – this depends on the state you live in and is too complicated to fully explain right now. (Call me if you really care, but be prepared for a nap attack.) For example, a person has worked enough to have 20 quarters of credit within the 10-years their disability started but they’ve worked for low paying jobs. Where the national average benefit is about $1,136 per month, that person’s actual benefit is $400 per month. SSI supplements that $400; which is why it’s called Supplemental Security Income. SSI is funded out of the Congressional General Budget. Right now (1/2/2023) the federal SSI rate is $841 per month for an individual (but just $1,261 for a married couple who both qualify). States may choose to add to the federal benefit. California adds $578.82 to the federal benefit; so the monthly total is about $1400 per month. (Those numbers went way up in 2023. In 2022 the combined benefit was less than $1,000.) People do not always get both. A typical SSDI recipient will get about $1,500 per month. That person will not get SSI too – that’s not quite true exactly; but again, call me if you really want a deeper understanding. This probably won’t cause a nap attack.
To qualify for SSI, a person needs to be living below the poverty level. Because the government is supplementing your RESOURCES they only pay if you really, really need it. For example, if a disabled person is living with someone (or couch surfing with friends) and is not paying rent, they are getting a free place to stay. Another example, a parent (who is under the full retirement age) is providing food, clothing, shelter etc. for their disabled child, the child’s needs are met. The government is not going to hand out money unless people need it. The couch-surfing person will not lose all SSI benefits, benefits will be reduced by about $250 per month. There are ways to deal with this – and, again, it’s too complicated to deal with here.
Side note: There are way too many Ss, Ds and Is to keep it straight. Think of the first program that depends on FICA earnings/quarters of credit as Disability. Think of the program for people who really, really need it as SSI.