Social Security's definition of legally disabled is different from that of other programs. The Social Security Administration (SSA) administers benefits to disabled individuals under two programs, Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI). SSDI is available to disabled individuals who have worked for a certain number of years and paid taxes into the Social Security program. SSI, on the other hand, is a needs-based program and eligibility depends upon a person’s income and resources. It is not uncommon for a person to qualify for both programs, although this will depend on a person’s work history and financial situation.
These federal programs are available only to those who meet Social Security’s definition of "disability," which is different from the disability definitions used by Medicaid and most private disability insurance policies. The Social Security Administration defines disability as:
An inability to perform work (what SSA calls "substantial gainful activity") that is caused by "medically determinable" physical or mental impairments which have lasted or will last at least 12 months, or will likely cause death.
SSA decides whether you meet this definition by following a five-step process.
First, SSA asks whether you are working and earning more than the "substantial gainful activity" threshold ($1,310 a month for 2021). If you are, you will usually not be considered disabled (unless you are blind).
Second, your condition must be "severe": significantly limiting your ability to do basic work tasks. If your impairments are not severe, you are not disabled.
Third, Social Security will decide whether your impairments meet those found in SSA’s Listings of Impairments, which lay out the criteria for many of the most serious disabling conditions to qualify for disability benefits.
If not, you move on to step four, which looks at whether you have the ability to return to any of your jobs from the previous 15 years. Social Security will assess the physical and mental requirements of your prior jobs, and determine whether you’re still able to perform them based on your "residual functional capacity" (RFC). Your RFC includes your physical ability to push, pull, lift, carry, stand, sit, and walk as well as your mental ability to follow directions, maintain attendance, and deal with co-workers and the public.
If Social Security decides your RFC prevents you from doing any of your past jobs, it will move on to step five, which asks whether there are there any other jobs that you can do. In making this determination, SSA will consider your age, education, work experience, and your RFC. In general, those who are older (over 50) and have little education are less likely to be found capable of adjusting to other work -- unless they have job skills they could transfer to less demanding work.
(Note that in some circumstances, Social Security can skip step four (whether you can do your prior work) and find you not disabled at step five if you can adjust to other work.)
(For more on this, see How Social Security Determines a Disability Claim.)
You will need to complete a disability application at your local Social Security office or over the phone. The application will ask about your health problems, daily activities, work history, and recent medical treatment. Your state’s Disability Determination Services (DDS) will then either approve or deny your claim at the initial level based on your application and your recent medical records. This decision may take several months, and only a fraction of disability applicants are approved at the initial level. If you are denied benefits, you'll need to appeal.
It is important to have documentation from your doctor about how your medical condition limits your ability to work. Claims examiners and administrative judges are supposed to give substantial weight to the opinion of your treating doctor, so it is often helpful to ask your doctor to submit a statement. For more information on providing good evidence, read about the medical evidence you need to prove disability.