little_apple said:
A non-resident visitor qualifies for a tax refund if the following conditions are met:
you are not a resident of Canada;
you purchased eligible goods, short term accommodation or both;
you paid GST/HST on these purchases;
you have original receipts;
the total of your purchase amounts (before taxes) for eligible goods and accommodation must be at least CAN$200;
each individual receipt for eligible goods shows a minimum total purchase amount (before taxes) of CAN$50;
the goods are removed from Canada within 60 days of the date they were purchased.
I don't think that rebate program is offered anymore, and it's replaced by a very specific set of conditions to get rebates on eligible purchases only (of which most people won't qualify for as it only involves conventions or tour packages): http://www.cra-arc.gc.ca/visitors/
A visitor CAN be determined a DEEMED RESIDENT of Canada if they are present in Canada for most of the year, and/or have a spouse in Canada.
http://www.cra-arc.gc.ca/tx/nnrsdnts/ndvdls/dmd-eng.html
http://www.cra-arc.gc.ca/tx/nnrsdnts/cmmn/rsdncy-eng.html
Of course if no income was earned, a tax return is really not required. But if you are doing one with no SIN, then you would need to register for an Individual Tax Number: http://www.cra-arc.gc.ca/E/pbg/tf/t1261/README.html