There are three main sources of income within the game.
Chairman Race Payments – This is based upon the target you select at the beginning of the season, with higher positions providing more money.
Sponsors – These are selected within the career and award money based upon finishing positions and on a per race basis.
Prize Money – This is awarded at the end of the season with the value dependant on your teams finishing position.
Since income is limited by these sources it is recommended to close eye on your expenses. Area’s such as HQ upkeep and team wages can become a heavy drain on your finances if not managed.