The key to this questions is where the goods and services are actually delivered. If people living in MI are the ones using the services in their state or else purchasing goods in a MI location, then such is where you pay sales tax and state tax. Where you physically are located is not relevant. It is where the goods and services are located which counts. If by contrast, you were providing services in WI and the people from MI were driving over to your location to pick up goods or else meeting with you in WI so as to use your services i.e. meeting with you in WI for a consultation, then you would pay sales and state taxes in WI. The location where the goods and services are delivered is what matters