Two disability programs are administered by the US Social Security Administration (SSA): Disability under Title II of the Social Security Act is referred to as SDI, which is funded via contributions made by the individual worker, and disability under Title XVI of the Act commonly is referred to as SSI, which is funded through general funds from the US Treasury. Both SDI and SSI disability adjudication use the same five-step sequential evaluation process to determine if a claimant fulfills SSA's disability definition. The foundation for determining disability under SSA is medical evidence that establishes a medically determinable impairment based on defined evidentiary criteria. SSA determines disability, does not rate disability, and awards disability benefits only for total disability. Unlike SSA, the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) does not determine (or rate) disability. The AMA Guides, Sixth Edition, emphasizes the use of evidence-based diagnosis for determining whole person impairments and contrasts with SSA disability for which a diagnosis is not a requirement and the focus is placed on determining «impairment» based on symptoms, clinical signs, and laboratory/diagnostic findings. SSA determines disability, does not rate disability, and awards disability benefits only for total disability. An impairment rating using the AMA Guides should not be equated to an SSA disability determination.