The GOP tax law, which lowered the federal corporate rate from 35 percent to 21 percent, is a "huge tailwind" for American businesses, Buffett said.
"It certainly means corporations will pay quite a bit less in tax than they otherwise would," he said. "When we make money in 2018 domestically, and subject to a lot of little things here and there, basically we'll be paying at 21 percent instead of 35 percent. That's a lot of money."
The 87-year-old Berkshire chairman and CEO released his annual report to shareholders on Saturday. It revealed that the company's net worth increased to $65.3 billion for the 2017 tax year, including $29 billion because of tax reform.
In a "Squawk Box" interview, Buffett explained the reasons for most of the gain.
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