The bills being drafted, as described by top Republicans and lobbyists, would affect family budgets across the United States, by altering tax brackets and some popular deductions, and investment decisions around the globe, by changing the way the United States taxes multinational companies. It centers on deep cuts to business tax rates, which Republicans promise will deliver income gains to middle-class workers.

Mr. Trump and Republican leaders in Congress released an outline of their plan in September, which included reducing the corporate income tax rate to 20 percent from 35 percent, a doubling of the standard deduction for individual income tax filers and the elimination of several widely claimed deductions for individuals. The framework put down a marker but left dozens of questions unresolved, many of them potentially worth billions of dollars to businesses and the federal government.

Business groups are meeting frequently with key Republicans, seeking to shape the bill, but no snippets of legislative text have yet become public.

However, party leaders cannot finalize a bill until another budget hurdle is cleared — the Senate and House must agree on a consensus budget document, which will include instructions for how much a tax bill could reduce federal tax revenues over the next decade. That document, which would be an agreement between the House and Senate, is crucial to allowing Republicans to change tax law without any Democratic support. Such agreement could come quickly or drag out over a week or more, depending on whether House members agree to the Senate version or demand substantial changes to it.

Republican leaders hope to finalize and introduce the House version of the tax bill as soon as early November, allow amendments from both parties in committee and on the House floor, and pass something by Thanksgiving. Senate leaders hope to pass a bill by December or early next year.

Democrats say that process does not allow time for careful consideration of the bill, or for the sort of bipartisan compromise that marked the 1986 effort.

“I can’t imagine that something this momentous would be done without hearings, when you consider they’re about to fundamentally alter the architecture of the nation’s revenue collection,” said Representative Richard E. Neal of Massachusetts, the top Democrat on the Ways and Means Committee.