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What Is a Certificate of Occupancy?

A Certificate of Occupancy, commonly called a CO, is a local government document that generally confirms that a building or a particular use has been approved for occupancy under applicable local requirements.

The exact terminology and process may vary among Nassau County towns, cities, and villages. Some properties may also have older certificates, completion documents, or other municipal records connected to renovations and approved uses.

Why Does a Certificate of Occupancy Matter?

A home may physically contain rooms or improvements that are not fully reflected in municipal records.

Examples can include:

  • A finished basement
  • A converted garage
  • An additional bathroom
  • A rear extension
  • A dormer
  • An accessory apartment
  • A deck
  • A detached structure
  • A change from one-family to two-family use

The fact that a feature exists does not automatically prove that it was legally approved.

What Should Buyers Review?

Before closing, buyers should compare the current property with the available municipal records.

Questions may include:

  • Is the home approved for its current use?
  • Are additions shown in the building records?
  • Was the basement legally finished?
  • Is the garage conversion documented?
  • Are open permits still associated with the property?
  • Does the number of legal dwelling units match the listing?
  • Are certificates available for major completed improvements?

Is a CO the Same as a Building Permit?

No.

A building permit generally authorizes work to begin under specified requirements. A Certificate of Occupancy or another completion document may confirm the approved use or completion status after required inspections and procedures.

A permit being issued does not necessarily mean that the project was properly completed and closed.

Can Missing Records Affect a Home Purchase?

Missing or inconsistent municipal records may affect:

  • Mortgage approval
  • Insurance
  • Appraisal
  • Closing negotiations
  • Renovation plans
  • Future resale
  • Legal use of the property
  • The cost of correcting prior work

The impact depends on the property, municipality, transaction, and nature of the issue.

Can a CO Affect the Property Assessment?

A Certificate of Occupancy is not a property-tax calculation. However, approved additions or changes in use may also appear in property and assessment records.

Homeowners should compare municipal building records with the assessment record to determine whether the property is being described consistently.

AIDOTAX helps homeowners organize assessment records and property information. Questions about legal occupancy, permits, or certificates should be directed to the applicable municipality and the buyer's attorney.

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