COS meaning in Real Estate ?

A certificate of occupancy is a document issued by a local government agency or building department certifying a building's compliance with applicable building codes and other laws, and indicating it to be in a condition suitable for occupancy.

The procedure and requirements for the certificate vary widely from jurisdiction to jurisdiction and on the type of structure. In the United States, obtaining a certificate is generally required whenever:

The purpose of obtaining a certificate of occupancy is to prove that, according to the law, the house or building is in liveable condition. Generally, such a certificate is necessary to be able to occupy the structure for everyday use, as well as to be able to sign a contract to sell the space and close on a mortgage for the space.

A certificate of occupancy is evidence that the building complies substantially with the plans and specifications that have been submitted to, and approved by, the local authority. It complements a building permit—a document that must be filed by the applicant with the local authority before construction to indicate that the proposed construction will adhere to ordinances, codes, and laws.