Is a 3 year undergraduate degree recognised in Canada and USA ??

I'm pursuing my B.Comm. which is a 3 year degree programme. somebody told me that a 3 year degree programme is not recognised if i wanted to pursue my postgraduation abroad as the standard degree programme in US and Canada are for 4 years, and that the colleges abroad require you to do one year extra study to formally recognise that you are a graduate according to college rules. Will somebody clear the air about this and tell me if its true or not ??