Answer
Gastos comunes are shared building expenses. They may include water and maintenance of the building and common areas; a more detailed breakdown may also include cleaning, lighting, elevators, staff, security, the garden, the pool, and building management.
Estimates range from 100 to 300 dollars per month or from 3,000 to 15,000 pesos. The range reflects the type of building, included services, heating, staff, and seasonal expenses.
Before signing the contract, ask for not only the total amount but also the most recent itemized bills. It is important to distinguish regular monthly expenses from extraordinary repairs to the façade or elevator, or from other capital assessments; these should not automatically become the tenant's responsibility under the contract.