You will need to obtain an EIN for the BC corporation; however, I would imagine a W8-BEN is not appropriate for you, if you are selling through Amazon FBA. The FBA program generally makes Amazon your agent in the US, which means any of your US source income, ie anything sold to a US customer is taxable in the US. W8-BEN is asserting that you either have no US sourced income or that income is exempt under the US/Canadian tax treaty. Based on the limited knowledge I have of your situation, but if you are selling through the FBA program, I would say you don’t qualify to file a W8-BEN, but rather should be completing a W8-ECI and your BC corporation should be filing an 1120F to report your US effectively connected income.