The Berlin City Tax is due for payment for bookings made for private overnight stays.
Business travelers are exempt from the City Tax and do not have to pay. They do, however, have to prove the business purpose of their trip.

Please read more on Berlin's tourist website: https://www.berlin.de/en/tourism/travel-information/3298255-2862820-city-tax-in-berlin-who-is-to-pay-how-muc.en.html