For Social Security and Medicare's Hospital Insurance program, the main source of income is taxes on wages and self-employment income. Taxes on wages are known as FICA (Federal Insurance Contributions Act) taxes and our FICA tax data include both employee and employer taxes. Taxes on self-employment are sometimes referred to as SECA (Self Employment Contributions Act) taxes. Both FICA and SECA taxes are deposited initially on an estimated basis, with subsequent adjustments for actual data.
Monthly employment tax data are available for each of the following trust funds: Social Security's Old-Age and Survivors Insurance (OASI) or Disability Insurance (DI) Trust Fund, or Medicare's Hospital Insurance (HI) Trust Fund. Please note that reports of these data are somewhat technical in nature and not all abbreviations are fully explained.