If you have income from the mainland, I believe you'll have to file a Federal return and you can file a Schedule E for rental properties. I believe you'll also, have to file a PR tax return for the income from PR. I don't think that you would have to set up a DBA or business. We currently own rental property here in Illinois. I'm curious about the tourist tax, too, as when we come to PR and rent from an owner, they've not charged us taxes.