⏳SSDI Back Pay Calculator

What it is

An estimator for SSDI past-due benefits — the lump sum covering the months between when entitlement began and when SSA approved the claim, built from your onset, application, and approval dates plus your monthly benefit amount.

How it works

Entitlement begins in the sixth full month after the established onset date (the 5-month waiting period, waived for ALS approvals on or after July 23, 2020). Payment can reach at most 12 months before the application month (20 CFR 404.621). The tool counts payable months from the later of those two boundaries through the month before approval.

Getting the most from it

1. Enter the established onset date from your decision letter — SSA's date, not necessarily the one you claimed.
2. Enter the application date; the 12-month retroactivity cap is measured from it.
3. Enter the approval date and your monthly benefit, from the SSDI calculator or your award letter.
4. Check whether the retro-cap warning appears — it explains why an early onset date may not add months.

Reading your result

The total is gross past-due benefits. SSA-approved representative fees (capped by law) are withheld from this amount before deposit, and offsets such as workers' compensation can change individual months — so the deposit can be lower than the estimate.

What it can't tell you

Before a decision exists, the established onset date is unknown — SSA sets it from the evidence, and every other date flows from it. This tool cannot predict that determination or any offsets; the arithmetic in SSA's award letter is the determination itself.