Your "alleged onset date" or AOD is that date that you say you became disabled. When you apply for Social Security disability, the interviewer will often ask you what date you believe you became disabled. For a lot of people, it is the last day they worked or the date of a serious accident, injury, or onset of an illness. This is the date that the original disability determination worker will use when ordering and evaluating your medical records. Onset date can be a very important factor in your Social Security disability case because you must have medical records that support a finding of disability back to the date you are alleging. It can also be very important if you have a date last insured issue. For this reason, it's important to know what your date last insured is and issues that may arise from it. Your onset date must be before your date last insured in order for you to receive Disability Insurance Benefits. In some cases, an Administrative Law Judge will ask you to consider amending your alleged onset date to better conform to the evidence in your file. It's important to be aware of when your alleged onset is and your reasons behind choosing that date. Administrative Law Judges in my area often ask clients this question during hearings. It's an issue that I always discuss with my clients prior to the hearing. Talking with an experience attorney can help you explore and resolve any issues you may have with your alleged onset date in your Social Security disability case.