On a conference call to discuss the report, a senior Treasury official said that about half of the difference between Treasury’s estimates for higher growth was based on the proposed corporate tax cut, which would reduce the tax rate for corporations to 20 percent from 35 percent. The rest of the difference is attributed to reducing taxes for “pass-through” businesses, whose profits flow through to their owners and are taxed at individual rates, and the administration’s plans for infrastructure, deregulation and changes to the welfare system that were outlined in the White House budget proposal this year.

“It’s not a dynamic score of the bill, because it includes regulatory reform, infrastructure and welfare reform,” said Douglas Holtz-Eakin, a conservative economist who was chairman of former President George W. Bush’s Council of Economic Advisers. “It looks to me like it’s a restatement of their budget.”

The impact of the Republican tax cuts on economic growth and the debt has been a subject of fierce debate among economists, with many arguing that the administration is relying on overly rosy assumptions.

“We acknowledge that some economists predict different growth rates,” the Treasury Department wrote in the report outlining its analysis of the plan.

Kevin Hassett, chairman of President Trump’s Council of Economic Advisers, said the Treasury analysis was “absolutely defensible.” He said that they started with the assumption that Mr. Trump’s economic policies would boost growth by about one percent per year over the decade and worked backward to demonstrate the effects of the tax cuts would not add to the deficit.

“If you just assume you would get that kind of growth, then you say how much revenue you get from that,” Mr. Hassett said on CNBC. “It’s all really just math.”

The Trump administration’s growth estimates have been at odds with those of government scorekeepers for much of this year. Last summer, the Congressional Budget Office analyzed the White House’s 2018 budget and found its estimate for 3 percent growth to be far-fetched. It said that the average gross domestic product growth over 10 years was currently 1.8 percent, and that under Mr. Trump’s plan it would be 1.9 percent — far lower than the rate assumed by the administration.