Occupancy Tax-what to do for guests who are exempt?

[Darryl-and-Bridgette0]

The state (Oklahoma) and our local  municipalities began charging these taxes and AirBnB collects and submits them. However, the law states that they ONLY apply to occupancy that is less than 28 days. Additionally, some guests (e.g., government workers on assignment) are exempt from those taxes. We regularly get interns, med students/resident physicians, and traveling nurses who stay for a month as well as military reservists who stay with us on their monthly duty weekends (and are thus exempt.) Does anyone else have any experience dealing with this issue and how do you resolve it?