Railroad retirement and survivor benefits are financed by the following sources of income:
- Payroll taxes on railroad earnings paid by covered employees and employers.
- Income from a financial interchange with the social security trust funds.
- Earnings on investments. Funds not needed immediately for benefit payments or administrative expenses are transferred to the National Railroad Retirement Investment Trust for investment (see Investments).
- Borrowing from general revenues related to certain features of the financial interchange mentioned in (2).
- Appropriations from general revenues.
- Revenues from Federal income taxes on retirement benefits.
Each of these income sources is described briefly below.