If
you’ve successfully filed your return to CRA’s NETFILE service and received a
confirmation number, you cannot make a correction and file again using CRA’s
NETFILE service.
Instead,
you’ll need to file an amendment.
Follow
these steps:
1. Check that the
CRA received your return
2. Follow these
instructions to amend your return
http://www.cra-arc.gc.ca/tx/ndvdls/tpcs/ncm-tx/chngrtrn-eng.html