First, read their actual report here: https://www.cbo.gov/publication/61270
They don't say anything about the actual number, just the percent of GDP. I previously projected GDP using forecasts from the Social Security Administration, which use an average nominal increase of 4.2% per year. So now we can see what the picture should look like 30 years in the future, based entirely on government sources.
Year GDP % of GDP Debt
==== ===== ======== =====
2025 31,000 100 31,000
2035 46,000 118 54,000
2045 70,000 136 95,000
2055 107,000 156 167,000
I rounded all the numbers to the nearest trillion. What will the interest on $167 trillion be annually? At 4%, it would be $6.7 trillion per year. Do you think this is sustainable? The CBO doesn't.
In CBO’s projections, federal debt, measured in relation to the size of the economy, surpasses its historical peak in 2029. That large and growing debt has significant economic and financial consequences. Over time, it slows economic growth, drives up interest payments to foreign holders of U.S. debt, makes the nation’s fiscal position more vulnerable to an increase in interest rates, heightens the risk of a fiscal crisis, and increases the likelihood of other adverse outcomes.
What adverse outcomes? They don't say, but either default on the national debt with or hyperinflation. Probably including a bloody civil war. Either way, the current system is unsustainable, and most people will lose everything. When will this happen? Certainly before 2055. I last projected 2042, but maybe it could last a few more years. So somewhere in the range of 2042 to 2054.
Update: Correction, they do forecast GDP as follows:
2025 30,100
2035 43,900
2045 62,900
2055 88,400
So they are actually projecting debt held by the public to be $138 trillion, not $167 trillion in 2055. But the warning remains the same - there will be increased likelihood of adverse outcomes.