The boon results from the diversified conglomerate lowering its tax liability on appreciated investments, according to Barclays. The measure of assets minus liabilities rose 12 percent, a number that corresponds to the earnings gain the company could receive, Barclays said. Morgan Stanley has put the earnings increase closer to 14 percent, according to Bloomberg, which first reported the Berkshire gain.

Congress passed a reform package that slashed the corporate rate from 35 percent to 21 percent while closing some loopholes and preserving others.

Buffett has long railed against corporate tax cuts, reasoning that his companies and others like it are doing just fine even with what had been the highest rate in the world.

"We have a lot of businesses... I don't think any of them are non-competitive in the world because of the corporate tax rate," Buffett told CNBC back in October.