President-elect Donald Trump's proposed tax cuts will primarily serve the middle class and will not include an absolute tax cut for the wealthy, Steven Mnuchin told CNBC on Wednesday, shortly after confirming he has been chosen to head the Treasury Department.

"Any reductions we have in upper-income taxes will be offset by less deductions so that there will be no absolute tax cut for the upper class," Mnuchin said in an interview on "Squawk Box."