Citadel's Ken Griffin said Monday that Republican efforts to cut back taxes may be going a bit too far.

"You would usually reserve tax reform of this nature for right in the midst of a recession," the billionaire said in an interview with CNBC's Leslie Picker. "Do we need to cut taxes as much as we are? Probably not. Do we need to reform taxes, simply taxes, and keep America competitive. Absolutely."

Griffin's hedge fund manages over $27 billion, while the CEO himself has a net worth of $8.6 billion, according to Forbes.

"If we look at the OECD means, which are in the mid-20s, I don't understand why we're not closer to that number. I would have thought we would have landed it somewhere around 25 percent for our corporate rate, not 20 [percent]. But not probably not worth splitting hairs over."

The GOP has been hard at work to pass tax reform before year's end, hoping to give President Donald Trump his first major legislative win. The House passed its own version two weeks ago. The Senate is expected to vote on its version this week.

Tweet

Importantly, the House bill would permanently lower the corporate tax rate to 20 percent from 35 percent, while the Senate's version seeks to abolish the Obamacare individual mandate. Though not unusual for politicians to debate the merits of a tax cut, some economists have been confused over the timing of the proposed relief.

"To the extent that this represents fiscal stimulus, this is a late-in-the-business-cycle-move," Griffin said. "It would be contrary to what you would traditionally do from an economics perspective."