Final answer:
The annual interest on the government's total debt is $275.6 billion. GDP must grow by at least 1.3% for the debt-GDP ratio to remain unchanged for a balanced budget before interest. With a $600 billion deficit in 2020, GDP would need to grow by 4.28% to keep the debt-GDP ratio stable.
Step-by-step explanation:
To calculate the annual interest on the government's total debt, we can use the formula Interest = Debt × Interest Rate. Given the debt of $21.2 trillion and an interest rate of 1.3%, the annual interest cost is:
Interest = $21.2 trillion × 0.013 = $0.2756 trillion or $275.6 billion.
For the debt-GDP ratio to remain the same when the government is running a balanced budget excluding interest, the GDP growth rate must be equal to the interest rate on the debt, which is 1.3%.
If the government incurs a deficit of $600 billion in 2020, the increase in national debt will be:
Debt increase = Initial Debt + Deficit = $21.2 trillion + $0.6 trillion = $21.8 trillion.
For the debt-GDP ratio to remain unchanged with a $600 billion deficit, the GDP must grow at a rate that is equal to the ratio of the deficit to the initial GDP plus the interest rate on the debt. If we denote the required GDP growth rate as G, then:
G = (Deficit / Initial GDP) + Interest Rate
G = ($0.6 trillion / $20.1 trillion) + 0.013
G = 0.0298 + 0.013 = 0.0428 or 4.28%
The debt-GDP ratio is preferred over the dollar value of the debt because it takes into account the size of the economy and its ability to repay the debt through taxation. A high debt-GDP ratio can constrain financial markets, crowd out private borrowing, and limit a country's ability to fund essential programs.