Other municipalities in Groningen
Outside the city of Groningen the pressure on the housing market is lower and the rules are lighter. Renting out one room as a resident hospita is usually permit-free.
Differences per municipality
Midden-Groningen has a housing ordinance with buy-to-let protection and a landlord permit, but most other Groningen municipalities have no strict room-rental quota. For hospita rental a conversion permit usually does not apply.
Check your municipality's housing ordinance or environment plan via lokaleregelgeving.overheid.nl.
For the national rules, see General rules for room rental. Also check the impact on your municipal taxes.