Not true.
US residents and/or citizens are taxed on worldwide income, no matter what the character (capital gains or ordinary). Plus you have to report foreign bank accounts or risk very high penalties.
Learn about global tax issues in my February article for SFO magazine. Go to
http://www.greencompany.com/Educatio...MediaSFO.shtml.
Trading Across Borders: The Tax Issues by Robert A. Green, CPA
Don’t leave home without them. Click here
http://www.greencompany.com/Educatio...lTraderTax.pdf for Green's original submission. The final SFO article is available on the SFO site for purchase, or pick up the print magaine.
When it comes to forex, always report your income, even though your broker may not report it to the IRS or if you have a foreign account. It is meaningless when you take money out of the account, you are taxed on the income as you make it each tax year.