In New York City, your home’s Certificate of Occupancy (CO) isn’t just paperwork. It defines legal use, unit count and occupancy. For buyers in Staten Island and Brooklyn, understanding whether a property is legally one-family or two-family is critical to avoiding fines, insurance issues or forced changes.

What a CO States

According to the New York City Department of Buildings (DOB), a CO states “the legal use and/or type of permitted occupancy of a building.” New York City Government For example, a CO for a one-family home will say something like “Use: Residential,” “Use Group: R3,” and indicate one dwelling unit. A two-family CO will say “two dwelling units” and might be a Use Group R2 or similar. Fontan Architecture+2Defalco Realty+2

Why the Difference Matters in Staten Island and Brooklyn

• Insurance and mortgage underwriters often check that the actual use matches the CO. If your home has two units but the CO says one, that mismatch can cause rejection or higher premiums.

• Many older homes were converted without amendment to the CO so what you see may not match the legal document.

• Selling or renting becomes risky if the CO is incorrect especially in neighborhoods in ZIPs 103xx / 11209 / 11214 / 11228 where multi-unit conversions were common.

• Changes in use (adding or changing units) require an amended CO; if you ignore it, you risk violations. New York City Government

What Buyers Should Do

• Pull the CO yourself via the DOB’s Building Information System to confirm unit count and use. New York City Government

• Compare what’s on the CO with what the property actually shows (units, entrances, separate meters, etc.).

• If there’s a mismatch, you can negotiate based on correction cost, or insist the seller remedy the CO before closing.

• If you plan to convert a one-family into two units, make sure you’ll be able to amend the CO legally.

Understanding COs and unit-counts in your Staten Island/Brooklyn deal protects value, avoids legal headaches and gives you bargaining power.

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Joseph Ranola | Five-Star Staten Island & South Brooklyn Realtor® (30 + Google reviews)
Associate Broker · Matias Real Estate | Founder · Bridge & Boro Team
Serving 103xx and 11209 / 11214 / 11228 | $25 M + closed volume
📞 917-716-1496 | ranolarealestate.com