Mnuchin also signaled a desire to remove U.S. mortgage-finance companies Fannie Mae and Freddie Mac from government ownership, a move that could have wide-ranging ramifications for how Americans pay for their homes.
The one-time Goldman Sachs banker, together with Wilbur Ross, Trump's nominee for commerce secretary, outlined Trump's economic agenda, including what Mnuchin called the largest tax overhaul since the Ronald Reagan administration, in an interview on CNBC.
Trump announced the economic team nominations, along with that of Chicago Cubs co-owner Todd Ricketts as Ross's deputy, in a statement on Wednesday.
Mnuchin and Ross reinforced the sweeping proposals Trump put forth in September to simplify the tax code and slash the corporate tax rate to 15 percent, cutting the top rate for all businesses from the present 35 percent.
"We think by cutting corporate taxes we’ll create huge economic growth and we’ll have huge personal income," Mnuchin said in the interview.
Tax experts have questioned Trump's assertion that the proposals would not add to the nation's debt and deficit. Mnuchin and Ross said lower tax rates would be offset by reductions in the number of income tax deductions.
"Taxes are way too complicated and people spend way too much time worrying about ways to get them lower,” Mnuchin said.
He also said the administration would cap mortgage interest deductibility but would allow for some deductions.
In a separate interview on Fox Business Network, Mnuchin said a major tax reform that includes a large middle income tax cut would be achieved within 90 days of the Trump presidency.
He also said he expected to reach 3 percent to 4 percent economic growth in the next couple of years. "I think it's very achievable," Mnuchin told FBN.
Mnuchin also told FBN mortgage giants Fannie Mae and Freddie Mac must get out of government ownership. Common shares of both, which trade on the lightly-regulated Pink Sheets market, shot up by around 30 percent to their highest levels in more than two years.
The two companies have operated under Treasury Department conservatorship since the 2008 financial crisis, when plunging home prices crippled their finances and threatened to bring down the U.S. financial system. Repeated efforts since then to reform the U.S. housing finance system have foundered in Congress.