A publicly available listing of US government expenditures is available for download at https://catalog.data.gov/dataset/public-budget-database-outlays-and-offsetting-receipts-1962-current. However, this lists all expenditures regardless of income source. Some subfunctions are funded in part or whole by special taxes (such as the social security tax taken out of your paycheck separate from federal taxes), while the majority come straight from income taxes.
Is there an official source that denotes which subfunction codes are paid for by these special trusts instead of federal income taxes, or is it up to citizens to research each individual line item?