US debt will become unsustainable and trigger default in about 20 years, if it stays on current path After 20 years, no amount of tax hikes or spending cuts could prevent default "whether explicitly or implicitly," according to Penn Wharton. https://markets.businessinsider.com/news/bonds/us-debt-crisis-gdp-ratio-unsustainable-default-treasury-bond-crash-2023-10