Enter 'Social Security' in the search box. Click on "Continue" under the Repay Your Social Security Overpayment Online section.Repay your Social Security Overpayment Online. The act created a uniquely American solution to the problem of oldage pensions. People have the right to appeal the overpayment decision or the amount. Use Form 843 to claim a refund of excess Tier 2 RRTA withholding.