CBO Finds Trump's Iran War Has Already Cost Nearly $40 Billion—And That's a 'Conservative' Estimate

President Donald Trump's illegal war with Iran has already cost US taxpayers almost $40 billion, according to a report released Tuesday by the Congressional Budget Office.

In total, the CBO report estimates that, by the end of July, the US Department of Defense had already spent $38 billion in operational, logistical, and sustainment costs related to the war.

CBO said this estimate reflects "the costs of replacing expended munitions and equipment lost in battle, increased flying hours, other operations, and increased fuel costs" for the department, as well as the fact that "the initial, intense phase of the conflict lasted just over a month... and that relatively few US forces have been involved compared with the much larger and longer US operations."

The office pointed out that it had to rely on government databases and public reports for data because the Pentagon didn't comply with its requests for more information about the war.

The report finds that the Iran War has also drained the military of missile defense interceptors, noting that the conflict "will leave the United States with a reduced inventory of interceptors for several years."

CBO's analysis also tries to measure the macroeconomic impact of the war, and concludes that it has made goods more expensive for US consumers by drastically raising the price of energy.

"In CBO's assessment, the effects of those higher energy prices will put upward pressure on consumer prices," the report explains. "As a result, in the first quarter of 2027, inflation (measured year over year) in the price index for personal consumption expenditures (PCE) is now estimated to be 0.5 percentage points higher than... projected in February 2026."

According to the most recent estimate from Brown University’s Watson School for International Public Affairs, the Iran War has now cost nearly $107 billion in additional fuel expenses for the public, averaging more than $776 per US household.

Rep. Brendan Boyle (D-Pa.), who requested the CBO estimate as ranking member of the House Budget Committee, ripped the Trump administration for blowing billions of dollars on an illegal war while insisting on taking an ax to the federal safety net via steep cuts to Medicaid and the Supplemental Nutrition Assistance Program (SNAP).

"Donald Trump and Republicans have spent years telling Americans that we cannot afford to help families here at home," said Boyle, "but apparently they can find tens of billions of dollars, and potentially much more, for a reckless war that is leaving Americans to pay the price."

Sen. Elizabeth Warren (D-Mass.) wrote in a social media post that the CBO's estimate of the war's costs was likely "conservative" because it excludes "damage to US bases, destroyed munition supplies, and higher costs like gas and groceries."