Having lived in Korea for 5 years and in the US for nearly 1, I can give some insight. The residency status is not something you can claim. If you're American you can do that--sadly, us Canucks cannot. Trust me, I know because I'm married to an American and we both lived overseas.
If you're paying
taxes in one country, double check to see if there's some kind of reciprocation so that you don't have to file in two countries. Living in the US I only file in the US as a resident--living in Korea I had to file in Canada because there was no understanding between the two countries.
While living in Korea I kept my bank account open, and kept my driver's license, as well as my credit cards. Every year I filed the bank accounts were not factored in--my accountant (who also is my family's accountant and has plenty of international experience) told me that there's an 80,000 cap (it can change year to year, but on average it's about that).
In terms of moving back--you need to keep your ducks in a row. Get some kind of official document from whatever tax office is in your country (in Korea every "gu" had a tax office of some kind). That way when customs/revenue comes knocking at the door you have proof that you paid taxes overseas (I still don't get why the Canadian govt thinks people don't pay taxes overseas, but you need to cover your butt). Next get an accountant who's not afraid of them--our yells back at them and hangs up if they're rude to him in any way shape or form.
Finally, the only time you'll have a difficult time is if you own property. That can really make living overseas a bit more complicated than it has to be--this can be stuff in storage, land, a car etc.
There are basically two levels that the government looks at when considering your residency/non-residency status...primary and secondary ties.
Primary is property, dependents, businesses etc.
Secondary is passport, drivers license etc.
http://dir.rbcinvestments.com/pictures/ ... status.pdfIt's the the govt that will determine your residency status. A bank account can also come into play if you're paying off a student debt, or still attending school while you're overseas--that's one good argument for keeping it open.