U.S. Debt Interest Payments to Surpass Defense Expenditures Within Decade

The Congressional Budget Office is estimating that annual interest payments on federal debt will more than double over the next decade to $778 billion.

Put another way, the U.S. will soon be paying federal debt interest (much of it to Asian and Middle East creditors) equal to the U.S.'s annual defense budget.

What assumptions lay behind the CBO's estimates? From the WSJ:

In 2010, it (the U.S. federal government) paid an average of about 0.1% interest on 3-month Treasury bills, and 3% on ten-year notes. Total net payments amounted to $197 billion, or 1.4% of annual economic output. That’s a bit more than what the government spent on unemployment insurance.

Low interest rates, however, won’t last forever — assuming the U.S. economy doesn’t succumb to long-term, Japanese-style stagnation. The CBO estimates that interest rates on 3-month bills and 10-year notes will reach 5.0% and 5.9%, respectively, by 2020. That, together with a rapidly rising debt load, would cause annual net interest payments to more than double by 2020 — to $778 billion, or a record 3.4% of GDP.

As bad as that sounds, I believe the CBO could be painting an overly optimistic scenario.

Whether the U.S. will actually be able to borrow long-term at a (historically) relatively low 5-6% interest rate in a decade's time is pure speculation by the CBO.

I'd also like to better understand why the CBO is projecting that U.S. interest rates across the yield curve will dramatically flatten? Right now the U.S. pays an interest rate of roughly 0.15% on 3-month borrowings, while the 10-year note is yielding 3.32%, for a difference of over 3% between short-term and longer-term borrowings. That's a pretty significant difference compared between the current level and the 0.9% difference the CBO is projecting in 2020.

If the U.S. continues its current debt trajectory is it reasonable to assume that it will be able to borrow long-term at a mere couple percentage points higher than today's levels?

Professor Barry Eichengreen is predicting that emerging financial powerhouses, such as China, will be able to offer a reserve currency alternative to the U.S. Dollar by 2020. The U.S. is undoubtedly realizing lower interest rates right now due to the European sovereign debt crisis, and the lack of any real alternatives to the U.S. dollar as the world's primary reserve currency and the unparalleled liquidity of the U.S. treasuries market. What will happen when (not if) the situation changes?

Interest rates can certainly rise faster and/or higher than the CBO is projecting. A recalculation by the bond market of the U.S.'s credit worthiness can occur suddenly, as we saw last year with Greece. Professor Niall Ferguson for one is predicting that a U.S. fiscal crisis, similar to the one experienced by Greece last year, will occur within 2-4 years.