Are there rules on how many workers can share accommodation in Oman?

Yes. Oman has worker-accommodation standards, and authorities carry out raids on illegal and overcrowded housing, especially in areas of Muscat like Muttrah and Hamriya. Workers found without valid papers, or living in breach of rules, can be detained, and those harbouring illegal workers can be fined. Before you rent, ask whether the accommodation is legal for workers and how many people share it. Overcrowding raises fire and health risks and can lead to eviction. If your employer is meant to provide housing, that accommodation should meet the standards. Keep your Resident Card and papers valid at all times, so a housing inspection does not turn into a residency problem for you.