You can go to the IRS’s website, and go through their multi-page question and answer pages. Make sure you’re ready with your SS-4, as the IRS may ask for that over the phone if it doesn’t like one of your answers. (PS, the IRS is not in the habit of liking.) Important note: you need some kind of tax identification to get a Tax ID Number. Usually that original identification comes in the form of an individual’s Social Security Number (usually the person forming the entity if it’s a small business). But foreign owners have a more difficult time doing this since they don’t usually have Social Security Numbers; in that case, they need to apply for an individual tax ID number, and then use that number to get the Tax ID Number for the corporation or LLC.