The windfall offset affects claimants who are eligible for retroactive Supplemental Security Income (SSI) and Social Security Disability Insurance (SSDI) benefits in the same month. The windfall offset prevents a claimant from receiving more benefits retroactively than he or she would have received if the benefits were paid during the month when they were due. The Social Security Administration (SSA) will pay the SSI benefits first to protect possible Medicaid eligibility in the retroactive period. The retroactive SSDI payments are reduced by the amount of SSI benefits paid for the same month.