
The United States government is financing its more than  trillion-dollar-a-year borrowing with i.o.u.’s on terms that seem too good to be  true. 
But that happy situation, aided by ultralow interest rates, may  not last much longer. 
Treasury officials now face a trifecta of  headaches: a mountain of new debt, a balloon of short-term borrowings that come  due in the months ahead, and interest rates that are sure to climb back to  normal as soon as the Federal Reserve decides that the emergency has  passed.
Even as Treasury officials are racing to lock in today’s low  rates by exchanging short-term borrowings for long-term bonds, the government  faces a payment shock similar to those that sent legions of overstretched  homeowners into default on their mortgages.
With the national debt now  topping $12 trillion, the White House estimates that the government’s tab for  servicing the debt will exceed $700 billion a year in 2019, up from $202 billion  this year, even if annual budget deficits shrink drastically. Other forecasters  say the figure could be much higher. 
In concrete terms, an additional  $500 billion a year in interest expense would total more than the combined  federal budgets this year for education, energy, homeland security and the wars  in Iraq and Afghanistan.
The potential for rapidly escalating interest  payouts is just one of the wrenching challenges facing the United States after  decades of living beyond its means. 
The surge in borrowing over the last  year or two is widely judged to have been a necessary response to the financial  crisis and the deep recession, and there is still a raging debate over how  aggressively to bring down deficits over the next few years. But there is little  doubt that the United States’ long-term budget crisis is becoming too big to  postpone. 
Americans now have to climb out of two deep holes: as  debt-loaded consumers, whose personal wealth sank along with housing and stock  prices; and as taxpayers, whose government debt has almost doubled in the last  two years alone, just as costs tied to benefits for retiring baby boomers are  set to explode.
The competing demands could deepen political battles over  the size and role of the government, the trade-offs between taxes and spending,  the choices between helping older generations versus younger ones, and the  bottom-line questions about who should ultimately shoulder the  burden.
“The government is on teaser rates,” said Robert Bixby, executive  director of the Concord Coalition, a nonpartisan group that advocates lower  deficits. “We’re taking out a huge mortgage right now, but we won’t feel the  pain until later.”
So far, the demand for Treasury securities from  investors and other governments around the world has remained strong enough to  hold down the interest rates that the United States must offer to sell them.  Indeed, the government paid less interest on its debt this year than in 2008,  even though it added almost $2 trillion in debt.
The government’s average  interest rate on new borrowing last year fell below 1 percent. For short-term  i.o.u.’s like one-month Treasury bills, its average rate was only  sixteen-hundredths of a percent. 
“All of the auction results have been  solid,” said Matthew Rutherford, the Treasury’s deputy assistant secretary in  charge of finance operations. “Investor demand has been very broad, and it’s  been increasing in the last couple of years.”
The problem, many analysts  say, is that record government deficits have arrived just as the long-feared  explosion begins in spending on benefits under Medicare and Social Security. The  nation’s oldest baby boomers are approaching 65, setting off what experts have  warned for years will be a fiscal nightmare for the government.
“What a  good country or a good squirrel should be doing is stashing away nuts for the  winter,” said William H. Gross, managing director of the Pimco Group, the giant  bond-management firm. “The United States is not only not saving nuts, it’s  eating the ones left over from the last winter.”
The current low rates on  the country’s debt were caused by temporary factors that are already beginning  to fade. One factor was the economic crisis itself, which caused panicked  investors around the world to plow their money into the comparative safety of  Treasury bills and notes. Even though the United States was the epicenter of the  global crisis, investors viewed Treasury securities as the least dangerous place  to park their money.
On top of that, the Fed used almost every tool in  its arsenal to push interest rates down even further. It cut the overnight  federal funds rate, the rate at which banks lend reserves to one another, to  almost zero. And to reduce longer-term rates, it bought more than $1.5 trillion  worth of Treasury bonds and government-guaranteed securities linked to  mortgages.
Those conditions are already beginning to change. Global  investors are shifting money into riskier investments like stocks and corporate  bonds, and they have been pouring money into fast-growing countries like Brazil  and China.
The Fed, meanwhile, is already halting its efforts at tamping  down long-term interest rates. Fed officials ended their $300 billion program to  buy up Treasury bonds last month, and they have announced plans to stop buying  mortgage-backed securities by the end of next March. 
Eventually, though  probably not until at least mid-2010, the Fed will also start raising its  benchmark interest rate back to more historically normal levels.
The  United States will not be the only government competing to refinance huge debt.  Japan, Germany, Britain and other industrialized countries have even higher  government debt loads, measured as a share of their gross domestic product, and  they too borrowed heavily to combat the financial crisis and economic downturn.  As the global economy recovers and businesses raise capital to finance their  growth, all that new government debt is likely to put more upward pressure on  interest rates.
Even a small increase in interest rates has a big impact.  An increase of one percentage point in the Treasury’s average cost of borrowing  would cost American taxpayers an extra $80 billion this year — about equal to  the combined budgets of the Department of Energy and the Department of  Education. 
But that could seem like a relatively modest pinch. Alan  Levenson, chief economist at T. Rowe Price, estimated that the Treasury’s tab  for debt service this year would have been $221 billion higher if it had faced  the same interest rates as it did last year.
The White House estimates  that the government will have to borrow about $3.5 trillion more over the next  three years. On top of that, the Treasury has to refinance, or roll over, a huge  amount of short-term debt that was issued during the financial crisis. Treasury  officials estimate that about 36 percent of the government’s marketable debt —  about $1.6 trillion — is coming due in the months ahead. 
To lock in low  interest rates in the years ahead, Treasury officials are trying to replace  one-month and three-month bills with 10-year and 30-year Treasury securities.  That strategy will save taxpayers money in the long run. But it pushes up costs  drastically in the short run, because interest rates are higher for long-term  debt. 
Adding to the pressure, the Fed is set to begin reversing some of  the policies it has been using to prop up the economy. Wall Street firms  advising the Treasury recently estimated that the Fed’s purchases of Treasury  bonds and mortgage-backed securities pushed down long-term interest rates by  about one-half of a percentage point. Removing that support could in itself add  $40 billion to the government’s annual tab for debt service. 
This month,  the Treasury Department’s private-sector advisory committee on debt management  warned of the risks ahead. 
“Inflation, higher interest rate and rollover  risk should be the primary concerns,” declared the Treasury Borrowing Advisory  Committee, a group of market experts that provide guidance to the government, on  Nov. 4. 
“Clever debt management strategy,” the group said, “can’t  completely substitute for prudent fiscal policy.”