#USNationalDebt The national debt is the amount of money that the federal government has borrowed to cover the outstanding balance of expenses incurred over time. In a given fiscal year (FY), when spending (e.g., money for roads) exceeds revenue (e.g., money from federal income tax), a budget deficit occurs. To cover this deficit, the federal government borrows money by selling marketable securities such as Treasury bonds, bills, notes, floating rate notes, and Treasury Inflation-Protected Securities (TIPS). The national debt is the accumulation of this borrowing along with the associated interest owed to investors who purchased these securities. As the federal government experiences recurring deficits, which is common, the national debt grows.