In Canada, if you have income, you are supposed to report it on your income tax form. Sales tax depends on the province you are in. If you are in a province with HST, then $30,000.00 is the cut off, less than that you may get a tax number and charge tax, or not. Over that, you have to get a tax number and charge tax. The up side of having the tax number is that you get a cut. The down side is the added overhead of keeping track. If you are in a province with separate GST and PST, then PST may have different rules. A local accountant should know the rules.
The other side of this is, if you are getting income, you can charge expenses against income which reduces the amount that is taxable as income.