The CBO said that the deficit was the largest since 1945 as it represented an estimated 15.2 percent of gross domestic product, making 2020 the fifth consecutive year the deficit has increased as a percentage of GDP.
It was also three times the deficit recorded in fiscal year 2019, with revenues dropping 1% and outlays rising 47% in 2020, according to CBOs estimates.
Thursday's estimate is based on statements from the Treasury Department, which is expected to release the actual deficit later this month.
The $3.1 trillion deficit is $180 billion smaller than the CBO's projection in September as revenues were $123 billion greater and outlays were $56 million less than originally projected.
CBO also noted the impact of the COVID-19 pandemic on the deficit, noting that the shortfall was 8% larger than 2019 during the first six months of 2020 but ballooned between April and September to eight times the size of the deficit during the same period in 2019.
The Committee for a Responsible Federal Budget said Thursday that Treasury data indicates debt has reached 102% of GDP, surpassing the size of the economy.
"It is hard to believe we now owe a full year's worth of output. We weren't supposed to cross this threshold for over a decade but here we are," said Maya MacGuineas, president of the Committee for a Responsible Federal Budget. "Debt is the size of the economy today and soon it will be larger than any time in history."