If your plan is to invest in US real estate then the following should be helpful.
In general, a foreign corporation or international investor that engages in considerable, continuous, or regular business activity in the United States is considered to be engaged in a trade or business within the United States.
Rental income and gains from the sale of real estate located in the United States is U.S. source income. Foreign corporations and trusts, and individuals who are neither U.S. citizens nor U.S. residents (“international investors”) are subject to U.S. income tax only on income that either is effectively connected with a U.S. trade or business (“effectively connected income,” or “ECI”), regardless of source, or, if not ECI, is still U.S. source income.
Mere ownership of unimproved real property or residential property held for personal use (for instance, an apartment or condominium) does not create a U.S. trade or business. Further, ownership of a single piece of property rented to one tenant on a net lease basis (i.e., where the tenant is required to pay all expenses connected with the real estate) does not give rise to a U.S. trade or business.
If a foreign corporation or international investor creates a foreign corporation to hold the investment, dividends paid by the foreign corporation are not subject to U.S. tax. Interest paid by the foreign corporation’s U.S. trade or business is U.S. source income and taxed and subject to withholding tax like interest paid by a U.S. corporation. Holding the US property in the Canadian corporation would mean amounts passed to you personally would not make you personally liable to file US return or be taxed in the US.
Holding the US property in a Canadian corporation would provide that the corporation would need to file and pay US tax on the income form the US property but you personally would be shielded form US tax yourself and the withholding of US tax that would apply if you used a US business structure to hold the property or held in your own name.