SSDI Back Pay Calculator
Estimate your Social Security Disability back pay, how it's reduced by the 5-month waiting period and 12-month retroactivity cap, and what an attorney contingency fee would cost. Free, instant, no data stored.
Estimated Back Pay
Benefits begin: Mar 2025 (onset + 5-month wait or 12-month retro cap, whichever is later)
How SSDI back pay is calculated
SSDI pays a lump-sum covering the period from when you should have started receiving benefits to when SSA actually approved your claim. Two rules reduce the amount:
- 5-month waiting period: No benefits are paid for the first five full months after your established onset date (EOD).
- 12-month retroactivity cap: Back pay cannot extend more than 12 months before your application date, no matter how early your onset date was.
Your eligible back-pay period starts at whichever date is later: (onset + 5 months) or (application date − 12 months).
Attorney contingency fees
If you used a disability attorney, SSA typically withholds 25% of your past-due benefits as their fee, subject to a cap (currently $7,200). The cap means attorneys receive the same maximum regardless of how large the back-pay award is once it exceeds $28,800.
Frequently asked questions
What is the PIA? Your Primary Insurance Amount — the monthly benefit SSA calculates from your lifetime earnings record. Find it on your Social Security Statement at ssa.gov/myaccount.
Does back pay include SSI? This calculator covers SSDI only. SSI back pay uses different rules (no waiting period, but benefits are offset differently). If you were approved for both, your attorney or SSA notice will break down each program separately.
When is back pay paid? SSA typically pays back pay as a single lump sum within 60 days of approval, though large awards are sometimes split across installments.