Alleged Onset Date (AOD) for Social Security Disability

Your alleged onset date on your Social Security application helps determine if—and when—you'll qualify for benefits.

By , Attorney · UC Law San Francisco
Updated by Diana Chaikin, Attorney · Seattle University School of Law
Updated 12/13/2023

When you first file your disability application, the Social Security Administration (SSA) asks you when you think your disability began—your alleged onset date (AOD). Your AOD plays a key role in the disability determination process.

What Does an Onset Date Mean?

An onset date is the date when you became disabled, whether by meeting a listed impairment or being unable to work at any job. Social Security calls your onset date your "alleged" (claimed) onset date until you've been approved for benefits, at which point you'll have an "established" onset date (EOD).

Why Is Your Onset Date Important?

If you applied for Social Security disability insurance (SSDI), your onset date determines how much in past-due benefits, or "back pay," you might get. The SSDI program offers up to 12 months in back due benefits, so having an earlier disability onset date means that you'll get a larger lump-sum payment.

Your onset date also determines when you become eligible to enroll in Medicare. And because Social Security doesn't pay short-term or "temporary" benefits, your AOD helps the agency decide whether your health conditions will be disabling for at least one year.

How Does Social Security Disability Decide When My Disability Starts?

Your disability date of onset must be related to a significant date in your work or medical history. Social Security looks at several factors to decide when your disability started. Common dates that Social Security might use for your onset date include:

  • the last date you worked full-time
  • the first date you received treatment for your impairment
  • the date of a medical record showing evidence of your condition
  • the date a doctor says you became disabled
  • the date of an accident that caused your disability, or
  • the first date that your symptoms became disabling.

Avoid picking an onset date that's unrelated to when you became unable to work. If you do, in the best-case scenario, Social Security can simply change your onset date to reflect one of the above factors, but in the worst-case scenario, the agency might doubt that you can't work and deny your application.

What If I Worked After My AOD?

Because your AOD is when you're saying you became unable to work, any earnings after that date will be carefully looked at by Social Security—especially if they reflect substantial gainful activity (SGA).

SGA is the amount of money you can make that the agency considers full-time work. The exact amount changes each year, but in 2024, making $1,550 or more per month is SGA. To be approved for benefits, you need to show that you have had (or will have) a period of at least 12 months since your onset date where you didn't earn (or won't earn) SGA.

Ideally, you won't have any earnings above SGA after your alleged onset date. But if you do, you don't necessarily need to restart the clock on your 12-month period, if you can get Social Security to view your earnings as an unsuccessful work attempt. If you worked for less than six months and had to leave because of your medical conditions—or your employer took away any special accommodations that were making it possible for you to work—Social Security is likely to see the earnings you made as an unsuccessful attempt to work, and it won't affect your AOD.

Can I Change My AOD?

Yes, you can "amend" (change) your original AOD to a different date. In fact, disability lawyers often advise their clients to agree to an amended onset date in exchange for a fully favorable decision (an approval) from an administrative law judge. Judges suggest amending your onset date when they agree that you're currently disabled, but disagree when your disability started.

The most common reason for amending an onset date is to match supportive medical documents. For example, if you claimed an AOD of January 30, 2022, but you didn't start seeing a doctor until March 14, 2023, you'll likely be asked if you wish to amend your onset date to the start date of your regular medical treatment, because that's when you started to have evidence of your disability.

Other reasons that a judge or attorney might suggest amending your onset date include:

  • a medical expert testified that you had a different date of onset
  • you changed age categories under the medical-vocational grid rules (for example, you turned 55 or 60)
  • your earnings after you applied didn't qualify as an unsuccessful work attempt, so the onset date has to be after that work ended
  • you collected unemployment after your AOD, or
  • you were incarcerated for a period after your AOD.

You don't have to amend your onset date. In that case, if the judge thinks you're disabled, they will choose an established onset date that's different from your AOD and will send you a partially favorable decision.

You can appeal the established onset date to the Appeals Council, but you run the risk of having the council reverse the entire decision and deny you benefits. Because the Appeals Council is less likely to reverse fully favorable decisions, it's generally better to amend your onset date to get a fully favorable decision.

Does My Social Security Disability Start on My Onset Date?

Not exactly. Even though your established onset date reflects when you became disabled under Social Security's regulations, you might not start receiving disability benefits until later. Your onset date does play a major part in calculating your "date of entitlement"—the date that Social Security begins to owe you money. Because SSDI benefits are subject to a five-month waiting period, your date of entitlement is generally five months after your established onset date.

Supplemental Security Income (SSI) benefits don't have a five-month waiting period, so your monthly benefits will start right after your established onset date, provided you meet the financial eligibility requirements for SSI.

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