Established Onset Date — EOD
The date SSA officially decides your disability began. It can differ from the date you claimed and controls how far back your SSDI back pay goes.
Official source: ssa.gov
## EOD vs AOD
When you apply for SSDI or SSI, you give SSA an Alleged Onset Date (AOD) — the date you say your disability started. After reviewing your medical records, SSA sets an Established Onset Date (EOD), which is the date SSA officially accepts.
If SSA's EOD is later than your AOD, your back pay shrinks — sometimes significantly.
## Why EOD disputes are common
The EOD is one of the most-appealed issues at Administrative Law Judge (ALJ) hearings. Common reasons SSA sets a later EOD:
- Gaps in your medical records around your claimed onset date. - A diagnosis that came later than your symptoms. - A Consultative Examination that downplayed early severity.
## How to support an earlier EOD
- Submit records from every treating doctor, hospital, and therapist. - Include a detailed Function Report describing daily limitations. - Ask treating providers for a written statement linking the onset of severe symptoms to a specific date. - At a hearing, your representative can argue for an amended EOD based on the full record.
## Why this matters in dollars
Every month of earlier EOD can add to your back pay — and SSDI back pay is paid as a lump sum. An EOD moved earlier by 12 months can mean tens of thousands of dollars more.
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Frequently asked questions about Established Onset Date
Can I challenge SSA's Established Onset Date?+
Yes. EOD disputes are one of the most common issues raised at reconsideration and ALJ hearings. Bring medical evidence that supports an earlier date.
Does an earlier EOD always mean more back pay?+
For SSDI, yes — back pay is calculated from your EOD minus the five-month waiting period, capped at 12 months before your application. For SSI, back pay starts the month after your protective filing date, regardless of EOD.
What evidence helps establish an earlier EOD?+
Treatment records, ER visits, imaging, mental health records, employer accommodations, and statements from treating physicians all help anchor the date your disability became severe.
What is the difference between AOD and EOD?+
The Alleged Onset Date (AOD) is the date you claim your disability began. The Established Onset Date (EOD) is what SSA officially accepts. They are often different.
Does EOD affect Medicare eligibility?+
Yes. The 24-month Medicare waiting period for SSDI recipients runs from your EOD plus the five-month waiting period.
Source: ssa.gov