"It's going to go through a process, and we expect the House and the Senate will get this to the president to sign this year, and we couldn't be more excited about the progress we've made," the Treasury secretary added.
In a speech Wednesday in Missouri, President Donald Trump stressed the need for tax cuts to make the U.S. more competitive globally. The administration's plans thus far have been short on details, but they generally seek to lower the corporate tax rate from the highest in the world at 35 percent to as low as 15 percent.
Mnuchin said the 15 percent rate is ideal, but he did not commit to that level.
"Wherever we end up, the objective is to get a competitive business rate," he said.
In addition, Trump is seeking to give companies tax breaks for bringing cash stored overseas back home.
Mnucin said repatriation also is a major goal of the plan.
"What's most important is that we end up with a competitive rate and we end up with a territorial system," he said. "That's what we've heard from literally hundreds and hundreds of businesses," he said.
Trump's goal of 3 percent growth is predicated at least somewhat on tax reform as well as regulatory rollbacks. Recent numbers have tilted in the administration's favor, with second-quarter GDP growth revised up to 3 percent.
Mnuchin said the difference between the trend growth of around 2 percent and Trump's aspirations for 3 percent is "trillions of dollars."
He also said he was not that concerned about a weakened dollar because it helps the U.S. in international trade.