- you are allowed to do it legally
- it is a bit of a tax headache, esp. if you also have to file in the USA (if you don't and you only have to worry about Canada, it's a bit easier). E.g. You are required to use the cost accounting method in Canada (as opposed to the accrual accounting method that is generally the default method in the USA).
- Depending on how much you expect to earn, you may have to register for an HST number (and collect/pay sales tax) (Can't remember the threshold, in my case I didn't make that much).
My suggestion to you is, it would probably be worth the consultation fee to visit a tax accountant to learn how to set things up right before you start... then after the first year it should be relatively easy.
