Gross interest on the public debt includes interest paid to government trust funds that hold Treasuries. Net interest removes that internal flow and shows what leaves the Treasury to outside holders.
For the first ten months of fiscal 2026 net interest was 931 billion dollars, up from 841 billion a year earlier, about 3 billion dollars a day. The Congressional Budget Office noted in 2026 that interest now costs more than national defence.
It is the line that compounds, which is why the paper puts it beside every new spending promise.