This is a good explanation of how the process works:
If your medical condition doesn’t match one found on the SSA’s List of Impairments, the SSA will evaluate your remaining abilities (called your residual functional capacity, or RFC) to see if you can do your prior job.
If not, the SSA will perform a medical-vocational analysis to determine whether there is other work you can be expected to learn to do.
About Residual Functional Capacity and Allowances
Your RFC is an assessment of what you are capable of doing and what you are too limited to do.
An RFC is a Residual Functional Capacity form. And its purpose is to do exactly what its name implies: rate the residual (i.e. leftover) functional capacity of a claimant after taking into account…
Your Disability File Materials
If you can show that you can no longer do the work you did in the past and you cannot perform other work, the Social Security Administration (SSA) will deem you disabled. To assess your medical condition as it relates to your ability to do past work or other work, the SSA will develop a Residual Functional
Your work history determines the requirements of your old job (and whether you can do it) and whether you have transferable skills to work at a new job.
If you don’t have a medical condition that qualifies you for immediate approval of disability benefits (called a “listing”), you’ll need to prove that you can’t work.
After you apply for Social Security or SSI disability benefits, Social Security sends your application to your state’s Disability Determination Services (DDS) agency. A claims examiner who works for DDS will request your medical records and then make a decision on your case. Claims examiners are overworked
Using the Medical-Vocational Grid Rules
Winning a claim for disability becomes easier the older a person gets. This is because the Social Security Administration (SSA) considers the fact that a successful transition to a new workplace or field for an older worker may be more difficult than for a younger worker (the SSA calls this a “vocational adjustment”).
If you are under the age of 50 when you apply for disability, it will be much harder for you to win your claim than for an older person. However, there are some tactics you can use to increase your chances of being approved.
When you apply for disability, if the Social Security Administration (SSA) decides your condition doesn’t meet a disability listing and you can’t do your past job, the SSA will refer to the “grid rules” for those between the ages of 50 and 54 to decide if you are disabled.
Advanced Strategies for Showing Social Security You Can’t Work
Your disability claim will be denied if Social Security decides you can do your past job or “other suitable work.”
If you were denied disability benefits because Social Security found that you could do your prior job, you’ll have to appeal to get a hearing in front of a judge.
If your disability claim is denied because Social Security says there is “other work” you can do (rather than your past work), you’ll need to request an appeal hearing in front of an administrative law judge (ALJ).
The whole website is very informative and has copies of many of the forms you’ll have to fill out: