The White House made its opening bid for what officials called the "biggest tax cut" in U.S. history —  with cuts that would benefit businesses, the middle class and certain high-earning individuals —  but left unanswered questions about whether the plan would be paid for, or how.

A list of goals for the tax overhaul, unveiled by President Donald Trump's top economic adviser Gary Cohn and Treasury Secretary Steven Mnuchin Wednesday, calls for slashing the federal income-tax rate to 15% for corporations, small businesses and partnerships of all sizes. It also imposes a one-time tax on about $2.6 trillion in earnings that U.S. companies have parked overseas. The plan would end the taxation of corporations' offshore income by moving to a territorial system, in which most foreign profits would be exempt from U.S. taxes. Currently, the U.S. taxes business income no matter where it's earned.

On the individual side, it proposes condensing the existing seven income-tax rates to just three, cutting the individual top rate to 35% from 39.6%. It would also end a 3.8% net investment income tax that applies only to individuals who earn more than $200,000 a year, repeal the alternative minimum tax and eliminate the estate tax, which currently applies only to estates worth more than $5.49 million for individuals and $10.98 million for couples.