Giving up your U.S. citizenship may mean you’ll be paying an Expatriation Tax.
If you expatriated after June 16, 2008, the new IRC 877A expatriation rules apply to you if any of the following statements apply.
• Your average annual net income tax for the 5 years ending before the date of expatriation or termination of residency is more than a specified amount that is adjusted for inflation ($147,000 for 2011, $151,000 for 2012, $155,000 for 2013 and $157,000 for 2014).
• Your net worth is $2 million or more on the date of your expatriation or termination of residency.
• You fail to certify on Form 8854 that you have complied with all U.S. federal tax obligations for the 5 years preceding the date of your expatriation or termination of residency.
If any of these rules apply, you are a “covered expatriate.”
Read more: http://www.irs.gov/Individuals/International-Taxpayers/Expatriation-Tax