NEW YORK - The One Big Beautiful Bill Act, which was signed into law on July 4, would add $3.39 trillion to the US deficit from 2025 to 2034, according to a report issued by the Congressional Budget Office (CBO) on Monday.

The latest estimate by CBO is higher than its estimate of $3.25 trillion made at the end of June, shortly before the act passed Congress.

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The increase in the deficit is estimated to result from a decrease in direct spending of $1.1 trillion and a decrease in revenues of $4.5 trillion, said CBO.

The tax and budget act represents US President Donald Trump's agenda policies, including tax cuts and funding boosts for military expenditure and border security.

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The mega act is highly controversial among lawmakers and Americans from different parties or income groups.

The act's huge effects on the US deficit in the coming years raised concerns from home and abroad.

The act is estimated to increase US borrowing by $4.1 trillion, with interest included, according to Maya MacGuineas, president of the Committee for a Responsible Federal Budget.

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"It's still hard to believe that policymakers just added $4 trillion to the debt. Many supporters of this law have spent months or years appropriately fuming about our unsustainable fiscal situation. But when they actually had an opportunity to fix it, they instead made it $4 trillion worse," said MacGuineas in a statement on Monday.

As of mid-2025, the US national debt stands at over $36.2 trillion, and the debt-to-GDP ratio has exceeded its peak during World War II.