Taxed when visiting the U.S.?

[ZhenYa]

To all U.S. expats who have established HK as a tax home. I was just unpleasantly surprised that I have to pay taxes for business trips to the U.S. Is that really true? What IRS publication says that? Thanks for all help.

[PDLM]

Yes - see Source of Earned Income on p16 of the IRS guide to tax for expats: http://www.irs.gov/pub/irs-pdf/p54.pdf