Originally Posted by
seawolf
If you are departing US for China, show check-in agent in US both passports. You've done your part in complying with US requirement to depart on US passport. In the unlikely event CBP raise a stink you didn't use your US passport to depart, the fault is with the airline as you presented both passports.
Show DE passport to Chinese immigration
Returning to US from China, show check-in agent in China US passport (and DE if asked).
Show DE passport to Chinese immigration
Show US passport to CBP
That sounds about right. What worries me mostly is when you have to show one passport to the check-in agent and another one to immigration. That always smells like trouble given how one would expect that data from check-in is passed on to immigrations, so if someone is checked in that doesn't show up in immigrations.
Originally Posted by
Loren Pechtel
Yup.
Showing multiple passports is fine so long as it is legal to possess them (if you were a China/US and showed both your Chinese one would be immediately cancelled as China doesn't permit dual citizenship), although you'll get a few clueless checkin people. (Hey, before you say I don't have a visa, why don't you notice the second passport rubber-banded to the one you're looking at?? You think I did that as a joke?)
In germany, you can legally have another country passport after you got a written permission from DE authority first, so i always fear that DE authorities will also want to see that permission or else some random german officer will keep the passport. Thats what happened once to a friend in the DE consulate that actually provided the permission - "oh yeah, our consular officers have no ideas what permissions someone else in the consulate handed out earlier".