In Czechoslovakia it was based on prewar censuses. Those with recorded German ethnicity and those who obtained German citizenship during the war were expelled. There were many exceptions, like antifascists, inhabitants of several regions, qualified specialists or spouses of non-Germans.

To your question: yes, those who didn't identify themselves as Germans weren't included.

Some Hungarians were also expelled, but on much smaller scale, usualy as a part of exchange for Slovaks from Hungary.