...found this in another thread, you might wanna have a look at it yourself:
You can't receive CCTB (or any other benefit -- maternal leave is the only one) while resident in a foreign country -- and CRA itself will decide if you are resident there, or in Canada, using their own calculations. In fact, before you leave Canada, you are expected to fill out a form which will let them determine this. Then, when you come back, you will have to fill out another form that determines whether you are now a resident of Canada. My wife and I didn't know about this, assumed that our PR status made us naturally residents (when we came back from 11 months in the States), and were surprised when after 10 months in Canada, CRA suddenly decided she wasn't a resident. It took us 15 months to get that decision reversed.
Increasingly Canadian agencies have access to tracking information from the border; and if they find out you've been receiving benefits while living abroad, they'll claw them back. It's not done in a hostile manner, but they are quite insistent about it; and if you don't pay, they will simply make them up from UCCB, tax refunds, other benefits, etc. The definition for 'living abroad' seems to be ~3 months.
http://www.canadavisa.com/canada-immigration-discussion-board/maternity-leave-outside-of-canada-ei-cctb-pr-renewal-t276555.0.html
