2013
A = Debt is around: $17.5 trillion
B = Debt Service: $416 billion
C = Average Rate: 2.38% ($416 billion / $17.5 trillion)
D = U.S. Tax Revenue: +/- $2.8 Trillion
Things won't get interesting until B approaches D.
So one way of looking at is if everything remained constant (which it won't) you'd need 15% interest rates on the current debt for debt service to approach tax revenue. If interest rates stay the same you could increase the debt to $128 trillion.
2013 A = Debt is around: $17.5 trillion B = Debt Service: $416 billion C = Average Rate: 2.38% ($416 billion / $17.5 trillion) D = U.S. Tax Revenue: +/- $2.8 Trillion
Things won't get interesting until B approaches D.
So one way of looking at is if everything remained constant (which it won't) you'd need 15% interest rates on the current debt for debt service to approach tax revenue. If interest rates stay the same you could increase the debt to $128 trillion.
Reference: Debt: http://www.treasurydirect.gov/govt/reports/ir/ir_expense.htm Debt Service: http://www.treasurydirect.gov/govt/reports/ir/ir_expense.htm Tax Revenue: http://www.usgovernmentrevenue.com/