Box 16A (CPP2) is for non-Quebec residents, Box 17A (QPP2) is for Quebec residents. I just tried completing my taxes again based on the comment in this thread that the issue seems to be fixed, however I am still getting the same error 90308. I also read "make sure you update Turbo Tax", how is this done if I'm using Turbo Tax online? I'm assuming this error is still not fixed.
