There are two types of disability benefits available to disabled Americans through the Social Security Administration (SSA). Social Security Disability Insurance (SSDI) provides benefits to Americans who used to be able to work and paid into Social Security during their working years but who are now disabled and are no longer able to earn an income. The amount of monthly disability benefits is determined by the length of your work history.
Supplemental Security Income (SSI) provides benefits to disabled Americans incapable of working who also have minimal assets. The amount of monthly SSI benefits is determined by statute and is currently less than $700 per month.
When you apply for either SSDI or SSI, you should allege the earliest possible onset date. With SSDI, your benefits can go back as far as one year prior to the date of your application. With SSI, you can only receive benefits as of the day of your application.
Additionally, with SSDI claims, there is a mandatory five month waiting period. That means that you will not receive SSDI benefits for the first five full months from the date you are deemed to have been disabled. Why the waiting period? No one really knows, but the SSA probably wants to make sure the disability will be long-lasting, and if you know you will not receive benefits for five full months, you might be less inclined to file a claim.