By Danielle Kucera, Sanat Vallikappen and Christine Harper

Eduardo Saverin, the billionaire co- founder of Facebook, renounced his U.S. citizenship before an initial public offering that values the social network at as much as $96 billion, a move that may reduce his tax bill.

Facebook plans to raise as much as $11.8 billion through the IPO, the biggest in history for an Internet company. Saverin's stake is about 4 percent, according to the website Who Owns Facebook. At the high end of the IPO valuation, that would be worth about $3.84 billion. His holdings aren't listed in Facebook's regulatory filings. Saverin, 30, joins a growing number of people giving up U.S. citizenship, a move that can trim their tax liabilities in that country. The Brazilian-born resident of Singapore is one of several people who helped Mark Zuckerberg start Facebook in a Harvard University dorm and stand to reap billions of dollars after the world's largest social network holds its IPO.

"Eduardo recently found it more practical to become a resident of Singapore since he plans to live there for an indefinite period of time," said Tom Goodman, a spokesman for Saverin, in an e-mailed statement.

Saverin's name is on a list of people who chose to renounce citizenship as of April 30, published by the Internal Revenue Service. Saverin renounced his U.S. citizenship "around September" of last year, according to his spokesman.

Singapore doesn't have a capital gains tax. It does tax income earned in that nation, as well as "certain foreign-sourced income," according to a government website on tax policies there.

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Exit tax
Saverin won't escape all U.S. taxes. Americans who give up their citizenship owe what is effectively an exit tax on the capital gains from their stock holdings, even if they don't sell the shares, said Reuven S. Avi-Yonah, director of the international tax program at the University of Michigan's law school. For tax purposes, the IRS treats the stock as if it has been sold.

Renouncing your citizenship well in advance of an IPO is "a very smart idea," from a tax standpoint, said Avi-Yonah. "Once it's public you can't fool around with the value."

Saverin previously scuffled with Zuckerberg, his Harvard University classmate, over his ownership in Facebook. Saverin sued him and settled for an undisclosed amount.

The 2010 movie "The Social Network" added to Saverin's fame after it portrayed him as a scorned friend who provided the company's early financing and then was squeezed out. In the film, written by Aaron Sorkin, Saverin was portrayed by Andrew Garfield, who will play Spider-Man in "The Amazing Spider- Man."

Saverin's investments
Saverin moved to the U.S. in 1992, and became a citizen in 1998, his spokesman said. He has invested in Asian, U.S. and European companies, according to his spokesman.

He plans to invest in Brazilian and in other global companies that have strong interests in entering the Asian markets. "Accordingly, it made the most sense for him to use Singapore as a home base," Goodman said in the statement.

His U.S. holdings include Jumio Inc., an online payments company, and ShopSavvy Inc., a price-comparison service.

Renouncing citizenship is an option chosen by increasing numbers of Americans. A record 1,780 gave up their U.S. passports last year compared with 235 in 2008, according to government records.

Income-tax rates for top U.S. earners will rise to 39.6 percent from 35 percent next year, and rates on capital gains and dividends also are scheduled to rise unless Congress blocks the increases.

'Tax cost'
"It's a loss for the U.S. to have many well-educated people who actually have a great deal of affection for America make that choice," said Richard Weisman, an attorney at Baker & McKenzie in Hong Kong. "The tax cost, complexity and the traps for the unwary are among the considerations."

Some of the world's largest wealth-management firms have ramped up efforts to fight tax evasion ahead of Washington's implementation of the Foreign Account Tax Compliance Act, known as Fatca, which seeks to prevent tax evasion by Americans with offshore accounts. HSBC Holdings Plc, Deutsche Bank AG, Bank of Singapore Ltd. and DBS Group Holdings Ltd. all say they have turned away business.

The 2010 law, to be phased in starting Jan. 1, 2013, requires financial institutions based outside the U.S. to obtain and report information about income and interest payments accrued to the accounts of American clients. That means additional compliance costs for banks and fewer investment options and advisers for all U.S. citizens living abroad, which may depress banks' returns.

Facebook plans to price its IPO on May 17, offering 337.4 million shares at $28 to $35 each. The shares will be listed on the Nasdaq Stock Market under the symbol FB. Morgan Stanley (MS), JPMorgan Chase (JPM) and Goldman Sachs (GS) are leading the sale.

To contact the reporters on this story: Danielle Kucera in San Francisco at dkucera6@bloomberg.n​et Sanat Vallikappen in Singapore at vallikappen@bloomber​g.net Christine Harper in New York at charper@bloomberg.ne​t

To contact the editors responsible for this story: Tom Giles at tgiles5@bloomberg.ne​t