WASHINGTON — President Trump’s proposal to slash individual and business taxes and erase a surtax that funds the Affordable Care Act would amount to a multitrillion-dollar shift from federal coffers to America’s richest families and their heirs, setting up a politically fraught battle over how best to use the government’s already strained resources.

The outline that Mr. Trump offered on Wednesday — less a tax overhaul plan than a list of costly cuts with no price tags attached, rushed out by a president staring down his 100-day mark in office — calls for tax reductions for individuals of every income level as well as businesses large and small.

But the vast majority of benefits would accrue to the highest earners and largest holders of wealth, according to economists and analysts, accounting for a lopsided portion of the proposal’s costs.

“The only Americans who are very clear winners under the new system are the wealthiest,” said Edward D. Kleinbard, a law professor at the University of Southern California and former chief of staff of Congress’s Joint Committee on Taxation, which estimates the revenue effects of tax proposals.