Here’s how much more debt US can take on before default becomes inevitable The US national debt tops $39.2T, and total debt including implicit obligations stands at over $108T, approaching the entire planet’s annual GDP. America is heading for a collision course with economic realities it abandoned in the 1980s. When debt reaches 210% of GDP, there’s no longer any “feasible tax on labor income that can finance interest payments…at returns acceptable to investors,” Fortune says