Most Social Security Disability claimants who are awarded disability benefits are eligible for back pay due to the backlog of processing for both Supplemental Security Income (SSI) and Social Security Disability Insurance (SSDI) claims. SSI back pay is paid retroactively back to the date the SSI claimant filed their Supplemental Security Income application, regardless of the date the claimant claims to have become disabled. Social Security Disability Insurance claimants may be able to receive back pay from the established onset date of their mental or physical impairment less a five month waiting period, with the caveat that the back pay will not be paid for more than 12 months before the date the claimant filed their application. Back pay may be paid in one lump sum for SSDI or in installments for SSI. Supplemental Security Income payments are paid in installment payments to ensure the Supplemental Security Income claimant does not exceed the resource and income limitation established by the Federal government for the Supplemental Security Income program.