'"ONSET DATE" AND WHY IT'S IMPORTANT

Social Security disability benefits place a great importance on what they call "onset date."  This is the date that your impairment or condition became disabling under the law.

Before it is proven, it's called "the alleged onset date" or AOD.  After it has been proven and accepted by Social Security it becomes known as the "Established Onset Date" or EOD.

The onset date is important for two reasons:

1.  It determines whether your disability began before your SSDI insurance coverage expired.  To be covered, your disability must have an onset prior to your Date Last Insured.  For example, if your Date Last Insured is 6/30/17, your disability must have an onset prior to 6/30/17 or it is not covered.

2.  It determines how much back pay you can receive, if any.  In most cases, Social Security will pay a benefit back to the date of onset, minus the five-month waiting period.  The further back the onset, the further back payments go.  

So, in a Social Security hearing, you aren't just trying to prove that you are now disabled, you are also trying to prove the onset date on which you first became disabled.