Numerous last-minute changes were made to the bill on Friday and in the early morning hours of Saturday.

One was to make state and local property tax deductible up to $10,000, mirroring the House bill. The Senate previously had proposed entirely ending state and local tax deductibility.

In another change, the alternative minimum tax (AMT), both for individuals and corporations, would not be repealed in full. Instead, the individual AMT would be adjusted and the corporate AMT would be maintained as is, lobbyists said.

Another change would put a five-year limit on letting businesses immediately write off the full value of new capital investments. That would phase out over four years starting in year six, rather than be permanent as initially proposed.

Under the bill, the corporate tax rate would be permanently slashed to 20 percent from 35 percent, while future foreign profits of U.S.-based firms would be largely exempted from tax -- both changes pursued by corporate lobbyists for years.

On the individual side of the tax code, the top tax rate paid by the highest-income earners would be cut slightly.

The Tax Policy Center, a nonpartisan think tank, analyzed an earlier but broadly similar version of the bill passed by the Senate tax committee on Nov 16 and found it would reduce taxes for all income groups in 2019 and 2025, with the largest average tax cuts going to the highest-income Americans.

Two Republican senators announced their support for the bill on Friday after winning more tax relief for non-corporate pass-through businesses. These include partnerships and other companies not organized as public corporations, ranging from mom-and-pop concerns to large financial and real estate groups.

The bill now features a 23 percent tax deduction for such business owners, up from the original 17.4 percent.

Democratic Senator Richard Blumenthal said Trump controls more than 500 pass-through companies that will directly benefit. "So the president may be celebrating, but most Americans will rue this day," Blumenthal said.

The Senate bill would gut a section of Obamacare by repealing a fee paid by some Americans who do not buy health insurance, a step critics said would undermine the Obamacare system and raise insurance premiums for the sick and the old.

Senator Susan Collins, a moderate Republican, said she obtained commitments from Republican leaders that steps would be taken later in separate legislation to minimize the impact of the repeal of the "individual mandate" fee.

Reuters