The Treasury released its monthly September 2026 and Fiscal Year (FY) budget data on October 16, 2026. As expected, it showed that interest on the debt exceeded national defense expenditures in FY 2026 and that as a percent of net Treasury receipts, interest on the debt reached 19.5%, the highest at least since 1940. Given the amount of marketable Treasury securities that have to be refinanced in the next three years, not to mention additions to the outstanding stock of Treasury securities due to persistent budget deficits, and given the current and expected level of interest rates, interest on the debt is on track to continue to grow absolutely and relatively. The Treasury is borrowing more and more just to pay the interest on its debt. With an upward-sloping Treasury yield curve (the yields on longer-maturity Treasury securities are higher than those on shorter-maturity issues), Treasury Secretary Bessent is shortening the maturity of outstanding Treasury securities by issuing new short-maturity debt and funding the buyback outstanding longer-maturity debt with short-maturity debt in an effort to mitigate the interest expense on the public debt. But if the Federal Reserve were to increase the federal funds rate in an effort to lower the inflation rate, this would frustrate Treasury Secretary Bessent’s plan. If the Federal Reserve were to reach an “accord” with the Treasury to keep the federal funds rate artificially low, the increase in interest on the public debt could be mitigated. This would be debt default by another name – higher inflation.
Let’s look at some data. Plotted in Chart 1 are the fiscal year observations of net interest payments on federal debt as percent of net receipts of the Treasury (the blue bars) and the monthly observations of the average interest rate on Treasury marketable interest-bearing debt through September 2026 (the red line). In FY 2026, net interest on the federal debt was 19.5%, the highest in decades. The last time interest as a percent of net budget receipts approached FY 2026’s level was in the mid 1980s through the late 1990s, when the average interest rate on marketable debt was considerably higher than it was in FY 2026. For example, the average interest rate on marketable Treasury debt in September 1991 was 8.058% as interest in relation to net receipts was 18.4%. As of September 2026, the average interest rate on outstanding marketable Treasury debt was only 3.518% while interest as a percent of net receipts was a full percentage point higher than it was in FY 1991. Obviously, the reason for this is that there is a much larger outstanding stock of federal interest-bearing debt.



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