It may be time for Facebook CEO Mark Zuckerberg to "unfriend" Uncle Sam.
Zuckerberg is expected to owe the IRS more than a billion dollars in taxes for 2012.
That is because Zuckerberg exercised a stock option and bought more than 60 million shares of Facebook when the site went public.
Even though we don't know exactly what he will owe, we do know the IRS will treat his stock options as income, which translates to roughly $2 billion.
On top of that, Zuckerberg's tax rate is close to 50 percent.
According to a Facebook regulatory filing, Zuckerberg knew the giant tax bill was coming, so he sold more than 30 million shares during Facebook's initial public offering to cover it.