The easiest way to look up a responsible party for a business is to look up the EIN for the business. An EIN is a public document and it can be viewed by anyone. Then see line 7a of this form for the name of the responsible party. If you know the state where the business is registered, you can search the records system of that state's corporations division. It's easiest to start with the name of the business, then view the details of the EIN for the responsible party. A sole proprietorship without an EIN won't have a responsible party.