Salient excepts from US Code title 26 § 877:

Expatriation to Avoid Tax:
This section shall apply to any individual if-
(A) the average annual net income tax ... is greater than $124,000
(B) the net worth of the individual as of such date is $2,000,000 or more
A nonresident alien individual described in subsection (a) shall be taxable for the taxable year...

Think that 1) you'll have a net worth of more than US $2M and 2) that the world will have better opportunities than the US? You should consider dropping citizenship before you hit the $2M mark, as you'll be liable for US tax over the next 10 years (currently). Keep in mind that countries typically have a 3-7 year holding period before you can become a citizen (real countries, not tax havens).

In 2008, the HEART act was passed which significantly alters the tax consequences of expatriation. Here is a good link: Specifically, there is no longer a 10 year tax on worldwide income. Instead, the expatriot's assets are evaluated, and income tax is calculated and levied as if all of those assets had been sold the day before expatriation. It appears that there are options to defer payment, but my guess is that the provisions (the effective interest rate accrued) are quite punitive. -- Theo

Good catch! Given the financial straits of many developed countries, I expect to see more laws like this to dissuade the wealthy from emigrating. Unfortunately, it just means that people who expect to become wealthy will emigrate sooner than later.... --Patrick