The Alledged Onset date, or AOD, is simply the date a person claims, or alledges (on the social security application), that their disability began.

Why is the AOD important?

The AOD potentially determines how much in past due benefits, or backpay, a claimant can receive.

For example, if a claimant alledged that their disability began on 9/1/99, and either an ALJ (Administrative Law Judge) or a Disability Examiner decided, based on a review of the medical evidence, that this was the case, a claimant would potentially be awarded benefits starting from that date (social security disability cases, however, are subject to a five month waiting period which, effectively negates five months of benefits--the fiver month waiting period does not apply to ssi cases). In almost any case, this would mean several thousand dollars in backpay.

In a case where a claimant is approved AND it is decided that the disability began when the clalimant alleged, the AOD would effectively become the EOD.

The EOD, or established onset date, is simply the decided commencement date for a claimant's disability.