CRA announces electronic filing requirements for GST and HST
Beginning July 1, 2010, all gst/hst registrants with annual taxable supplies over $1.5 million (in addition to some other less common situations contained within the release) will be required to filing electronically.
Although these changes are only in effect for those mentioned above, the Government encourages all registrant to filing their gst/hst returns electronically.
The full release can be viewed here.