Further, the rules governing many of these benefits have become increasingly more complex, with Congress drawing a zigzag line (sometimes a disconnected line) on which side of a potential benefit a taxpayer will fall.

FORBES: Astronomy and the Federal Tax Law

Bill Brown from Duke University, law professor and expert in financial services, told the BBC's World Service that this latest settlement with Fannie Mae was drawing a line under the whole subprime mortgage-backed securities saga.

BBC: Bank of America sign