The withholding tax rate and any exemptions available depend on the tax treaty that Canada has signed with the country where the company issuing the stock is located. For stocks from some countries, investors may be able to reduce the tax on dividends by completing some paperwork. For example, the standard dividend withholding tax rate for U.S. stocks, the most popular foreign stocks held by Canadians, is 30 per cent, but if you file a U.S. Internal Revenue Service Form W-8BEN with your broker, the rate is lowered to 15 per cent.