More than half of the $9 trillion in debt the US Federal government is expected to build up over the next decade will be incurred to pay interest charges – US$4.8 trillion.  In 2015 the projected $533 billion in interest payments payable by the US Federal government will be equal to a third of the federal income taxes expected to be paid that year – obviously a dangerous trend given that longer term interest rates can be expected increase from their currently historically low levels.  The other issue for the US is that the duration of its borrowing is rather short – in simple terms that means the US federal government must constantly refinance its existing debt in addition to borrowing more to fund ongoing deficits. The magnitude of this issue is shown in that the US Treasury estimated in November 2009 that “approximately 40 percent of the debt will need to be refinanced in less than one year.”  This shortened duration leaves the US quickly exposed to any increases in borrowing costs demanded by the markets.  Will the US Federal Reserve simply print the money to fill the gap?