As a practical matter, most claimants will receive their back-pay payment within 60 days of receiving the approval notice.
Because of the length of time that a Social Security claim takes to go through the administrative and adjudication processes, past due benefit (or backpay) is nearly always awarded.
The amount of backpay that a claimant is due depends on when the disability was determined to have begun, and when the claimant initially filed for disability.
For SSI claims, social security backpay accrues from the date of the initial application. For SSD claims, Title II and RSDI claims, benefits accrue from the date of the application, and can go back an additional twelve months, depending on the Established Onset Date (EOD). However, there is a mandatory five month waiting period for such claims that will ultimately affect the amount of backpay that the claimant will receive.
The Established Onset Date (EOD) may be decided either by the administrative law judge or by Disability Determination Services (SSD), and is meant to determine the exact date (or as close an approximation to the exact date) that the claimant first suffered disability.