San Francisco Chronicle / Nicholas Carlson

Facebook CEO and cofounder Mark Zuckerberg is going to have to pay $1.5 billion in income taxes after the company's shares begin public trading in May, the Financial Times reports.

The reason: In 2005, Zuckerberg was granted new stock options as part of his compensation.

Facebook says that those options will be excercised after the IPO.

That means Zuckerberg will buy them for how much they cost back then.

The difference between that price and how much Facebook shares will trade for after the IPO will be considered taxable income.

The tax bill reduce Zuckerberg's wealth to a mere $24 billion.

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Read more: http://www.businessinsider.com/mark-zuckerberg-will-have-to-pay-15-billion-in-taxes-after-the-facebook-ipo-2012-2#ixzz1lMLo3JFG