EXCLUSIVE: Watchdog Says Congressional Budget Office’s Calculations Have More Holes Than Swiss Cheese

A report from a government watchdog organization released Thursday highlights inaccurate projections from the Congressional Budget Office (CBO).

The report released by Open the Books spotlights decades of CBO projections and finds that while routine estimates were normally reliable, projections tied to larger legislation missed the mark. According to the report, the CBO’s scoring is generally accurate, although projections for major legislation frequently are missed by wide margins, with revenue estimates showing larger deviations over time.(RELATED: Blue States Turbocharging Their Own Collapses With New Tax Gambits)

The report notes that CBO’s miscalculations have continued to grow over the years. From 1983 to 2024, the average error in CBO projections was 6%, according to the report.

In February 2009, the CBO projected that a $25 weekly unemployment insurance bonus would cost taxpayers $39.2 billion over a ten-year period. After six years, the CBO issued a revised estimate showing it would actually cost $64 billion, a 63% increase over initial projections.

Notably, the Affordable Care Act, passed under the Obama administration, became one of the largest federal expenditures and was more expensive than the initial CBO cost estimate in 2010, which projected $788 billion. When the CBO conducted another estimate two years later, it ballooned to $1.76 trillion, a 123% jump.

Michael Solon, senior fellow at the Hudson Institute, told the Daily Caller News Foundation that the issue may extend beyond legislative scoring alone, arguing that broader economic forces often outweigh policy changes.

“The economic factors are far more important than the legislative factors,” Solon said, noting that shifts in economic growth can have a significantly larger impact on federal revenues than individual pieces of legislation.

Solon noted that legislative estimates draw the most attention, but they represent only a small slice of what drives budget outcomes.

“Scoring is not forecasting.” Douglas Holtz-Eakin, former director of the CBO, told the DCNF. Holtz-Eakin argued that the process guarantees to make the CBO marginally inaccurate.

When asked about the large miscalculation with the ACA, Holtz-Eakin noted, “The baseline they were scoring off was more than a year and a half old. Of course it was going to be wrong.”

“The ACA looks different in 2012 than it did when it was first passed,” Holtz-Eakin said “There’s no way CBO can anticipate that,” he further stated.

The CBO didn’t immediately respond to questions from the DCNF about the report.

The report also noted that the CBO plays a significant role in shaping legislation, as the office works directly with legislators during the bill-writing process.

The costs for running the CBO ballooned to $75.8 billion in fiscal year 2026, an 8.2% jump from the previous year. The CBO is also exempt from complying with the Freedom of Information Act; information such as salaries remain hidden from the public according to the report.

The CBO’s primary focus on budgetary projections has shifted slightly since the early 2000s, as it has become involved in climate-related policy. Over the years the budget has become inflated with climate-related funds, and currently nears $1 trillion.

The report highlights the CBO’s flaws in analyzing climate data. In 2021, the CBO released “Budgetary Effects of Climate Change and of Potential Legislative Responses to It.” In the report, the CBO flagged climate change as a risk to budget deficits, adding that mitigation or adaptation could reduce climate change costs, but that the “benefits of successful investments would generally accrue gradually over many years and might be only partially reflected in future savings to the federal budget.”

As the rising national debt approaches $40 trillion, unfunded liabilities including Social Security and Medicare will increase as baby boomers continue to retire, further straining the federal budget. These mandatory spending programs account for approximately 60% of federal spending.

A decline in the U.S. Labor force participation rate is expected to further strain the already bloated federal budget, with the rate dropping to its lowest level since 1977, The Wall Street Journal reported. 

The report calls for greater transparency, higher accuracy and reduced reliance on the CBO as the sole authority for budgetary and economic information in Congress.

Republican Kentucky Rep. Andy Barr introduced legislation in 2025 to strengthen budget accountability, requiring the CBO to publish supplemental analyses of major legislation before major legislation receives a vote. “Washington’s budget process is broken, and part of the problem is that there’s no accountability when reality doesn’t match the promises made to get legislation passed,” Barr said in a statement.

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