Icahn super PAC adds fuel to big money fight in DC

Carl Icahn: I'm pledging $150M to form super PAC

When Carl Icahn takes his corporate tax reform fight to Washington, he'll join top American companies already funneling money into changing the way the U.S. handles corporate profits.

The billionaire activist investor announced Wednesday he would commit $150 million to a super PAC to prompt legislative reform on tax "inversions," or when a company changes its domicile to receive lower rates elsewhere. He proposes a lower "double tax" on cash brought back into the U.S. by American firms to discourage them from keeping money abroad or leaving altogether.

Read MoreIcahn: I want to see something done in Congress

On Wednesday, Icahn told CNBC he would use the funds to hold a "dysfunctional" Congress "accountable." While he didn't detail specifically how his money would spark reforms, it's another large cash injection into an issue companies continue to put their weight behind.

Carl Icahn at Delivering Alpha 2015 in New York.
Adam Jeffery | CNBC

Icahn cited Pfizer and Monsanto as "foundational American companies" that recently considered overseas deals. Both have lobbied Congress on tax issues this year, with Monsanto citing "international and corporate tax reform" during a second quarter in which it spent $1.3 million on lobbying, according to Senate disclosures.

Pfizer, which reported nearly $1.8 million in second-quarter lobbying expenses, also mentioned "comprehensive tax reform."

Icahn, one of the largest Apple shareholders, also has a personal interest in reform. Apple holds about $180 billion in cash abroad.

The tech giant has also been active in Washington, citing "international" and "corporate" tax reform in its third-quarter activity. Apple spent $980,000 on lobbying in the quarter.

Icahn stressed to CNBC on Wednesday "Apple is not going to leave this country."

Read MoreWhy bringing corporate cash home won't help

The lobbying disclosures do not clearly outline which policies the companies would support. Pfizer, Monsanto and Apple did not immediately comment on what type of tax reform they would want to see.

With Icahn's big-money involvement, the issue is unlikely to fade in the near future. It was already a debated topic after the Obama administration threatened tougher restrictions on corporate inversions last year.

In a letter Wednesday, Icahn said he had already reached out to Democratic Sen. Charles Schumer and possible House Speaker Paul Ryan about his reform ideas.