A tax system overhaul along the lines that Mitt Romney has proposed would give big tax cuts to high-income households and increase the tax burden on middle- and lower-income households, according to an analysis from economists at the Tax Policy Center.

The researchers did not analyze the exact Romney plan, since it is incomplete and the researchers were reluctant to make assumptions until the campaign released more details.

Instead they created a model for a revenue-neutral income tax change that incorporates some of Mr. Romney’s proposals, which include lowering marginal tax rates, eliminating both the alternative minimum tax and taxation of investment income of most taxpayers, doing away with the estate tax and repealing the additional high-income taxes passed with the Affordable Care Act.