WASHINGTON (Reuters) – The U.S. Treasury on Thursday announced new proposed rules for a new corporate alternative minimum tax that is expected to generate $250 billion in U.S. revenues over 10 years from about 100 large companies now paying an average rate of just 2.6%.

The Treasury said in a statement that the tax would apply to companies with annual average adjusted financial statement income of $1 billion or more. These companies often use income deductions and other strategies to minimize their net income and federal income tax, in some cases to zero.

Treasury officials declined to identify the 100 companies that likely would be subject to the tax, but added that they are now estimated to pay an average effective tax rate of 2.6% after deductions and credits, with about 60 paying less than 1%.

The new tax was approved as part of the 2022 Inflation Reduction Act to help offset the cost of hundreds of billions of dollars worth of new clean energy tax credits.

“The proposed rules released by Treasury today are an important step toward realizing Congress’ efforts to address the most egregious U.S. corporate tax avoidance and ensure the largest and most profitable corporations in the country cannot pay little to no taxes,” U.S. Treasury Secretary Janet Yellen said in a statement.

She said the new tax would help level the playing field for small businesses, who do not have access to expensive tax lawyers and advisers to devise complicated tax reduction strategies.

The rules published in the Federal Register on Thursday provide additional clarity on limitations for deductions that can be applied to determining adjusted financial statement income and tax liability, officials said.

Although there is a general requirement for companies meeting the $1 billion profit threshold to pay the 15% alternative minimum tax, the more specific clarifications contained in Thursday’s proposed rules would apply to the 2024 tax year, Treasury officials said.

The Treasury said it will accept public comments on the proposed rules on until Dec. 12, including requests to speak at a hearing on Jan 16, 2025.

(Reporting by David Lawder; Editing by Chizu Nomiyama)