The rent of departments is an activity that requires a concerted effort by all the involved parts, the renter and the landlord. First it must show continuously the building and it hopes to that the next supply is the best one, and the landlord must see many options of rent of departments, compare, consult and soon to supply, as long as there is not anybody does it first. But against the price settled down for the rent of the department, both participants in the transaction can negotiate the contract. Both have arms to do it. Who rents the department must be pending of adjustments that the building needs, like being walls with humidity, bath or cooks in evil been, doors or windows that need spare part. The landlord will be able to realise the rent of the department to a smaller price to the awaited one, but something greater to the solicitd one by the renter. If the adjustment to realise is very small and in addition some provable advantage exists, another supply will be able to be realised superior. Factors like the luminosity, the ventilation, the proximity with streets where is much transport, with the financial center or a park is some of so many to use. The rent of departments does not save to the law of the supply and the demand, of it throws and it relaxes. Perhaps a small reduction in the tariff will make of the renters people more thanked for and careful with the building, allowing at some future date to rent it or to sell it to other people expensive, without needing repairs. If the renter abuses the negotiation the rent of the department he will be without doubt for another person, or if it happens the same with rents that it will be able to take long time before beginning to redituar the investment that realised in the building.