CBO said Wednesday federal debt held by the public at the end of FY 2015 was 74 percent of gross domestic product, the highest annual debt-to-GDP ratio in 65 years.
The agency calculates public debt by adding annual deficits and surpluses and says federal credit programs, including financial aid to students, can also affect overall debt.
The government spent a total of $3.7 trillion on discretionary defense and nondefense programs as well as on mandatory benefits such as Medicare, Medicaid and social security, according to the report.
Revenues from corporate, payroll, individual and miscellaneous taxes amounted to $3.2 trillion during fiscal 2015, the report noted.