Social Security Disability Insurance (SSDI) and Veterans Disability Compensation (VDC)–administered by the Social Security Administration (SSA) and the Department of Veterans Affairs (VA) respectively–are two of the largest federal disability programs, but strongly differ along several dimensions, including the populations served, how each program defines a “disability,” as well as varying eligibility requirements. First, SSDI is an insurance program that replaces a portion of earnings for an eligible worker whose illness or injury–while not necessarily caused by a work-related incident–results in an inability to work. SSDI is one of several federal programs funded through the Federal Insurance Contributions Act (FICA) payroll tax and the Self-Employment Contributions Act (SECA) tax to which all workers and employers in covered occupations (including military personnel) and self- employed individuals make contributions. On the other hand, VDC is not insurance, but is a compensation program in that payments are made to veterans who develop medical conditions that are related to their service in the military.