online sales taxes?
cperciva: Does that count as an export?Yes.  If you provide a service to people outside of Canada, this counts as an export and is zero-rated (i.e., 0% tax).Do I have to register my business in the jurisdiction of wherever I sell (that sounds silly, but I need to know for clarity!)?No.  Unless you have a presence in a jurisdiction (approximately defined as "have an office", but the exact rules vary -- simply renting a server somewhere doesn't count, though) you don't have to deal with that jurisdiction's sales taxes.As an Ontario company, you'll need to deal with Ontario's RST (for Ontario customers only) and GST (for Canadian customers only).  You don't need to worry about US sales taxes, you don't need to worry about European VATs, and you don't need to worry about other provincial sales taxes (unless you set up an office in another province).Provincial and federal sales taxes are enough to worry about, though -- because depending on how your service is categorized you might have to charge a different sales tax rate or none at all.  I ran into enough ambiguities in the rules that for tarsnap I'm taking the simple approach of not accepting Canadian customers for now -- because the only thing I could be absolutely sure about was that I didn't have to charge any tax to non-Canadians.