One of the last-minute, late-night changes Senate Republicans made to their tax overhaul plan may mean higher taxes for corporations, including technology firms, than the bill's drafters intended, experts say.

As amended, the Senate tax bill would preserve the existing 20% corporate alternative minimum tax, a levy designed to stymie companies' tax avoidance that applies to fewer than 1% of U.S. companies under current law.

But under the Senate plan, retaining the AMT could prevent companies from making use of planned tax breaks related to intellectual property, spending on new equipment, and research and development. The AMT may fall hardest on technology and utilities companies—though the snag would apply broadly, experts say.