According to BBC, last year the Federal Reserve made over $51.1 in revenue last year, allowing them to pay a record $46.1 billion to the U.S. Treasury. This number represents the largest payment made to the Treasury since 1914. It was also a massive 47% increase from the year prior. As the BBC article explains, the record figure was largely a result of the Reserve’s attempts to support financial institutions with large bail out loans.
The Federal Reserve funds itself from its own operations and returns any profits to the Treasury department.
The figures suggest that US taxpayers have, so far, gained money from the US government's action in propping up the system. Some of the profit has come from interest earned on government bonds and mortgage-related securities, including those of mortgage giants Fannie Mae and Freddie Mac.
The emergency lending programs instituted by the central bank during the last year's financial crisis helped swell the Fed’s balance sheet to more than $2tn. They were designed to keep down interest rates and get banks lending to each other again, hoping to spark an economic recovery.
The Federal Reserve could also lose money on its holdings if it sells them at a time when they have fallen in value. The Fed also earned money from its emergency loans to banks and other firms, such as the giant carmakers. It charged both interest and fees on these.