Illegal Conversions in NYC: $15,000 Per Unit and $1,000 a Day

What counts as an illegal conversion

Administrative Code 28-210.1 makes it unlawful to convert any dwelling for occupancy by more families than the number legally authorized - the number on the Certificate of Occupancy - or to assist, take part in, maintain, or even permit the maintenance of such a conversion. The last part matters: the charge runs against the owner who tolerates the condition, not only against whoever built it.

The typical fact patterns are an apartment subdivided into two or more units, a cellar or basement fitted out as a dwelling without the required egress, light and air, and rooms rented out as separate households. A conversion does not become legal because it is old, because the tenants are quiet, or because no one complained for years.

The penalties stack three deep

An illegal-conversion summons carries the Buildings Penalty Schedule penalty for the infraction, and two further layers can sit on top of it:

• The daily penalty runs until the correction is certified. The Department's own instructions are blunt: submit an acceptable Certificate of Correction before the first scheduled hearing date to stop the accrual.
• The owner has a narrow defense where the conversion was genuinely unknown to them and they moved promptly to address it once the violation issued - it is a defense to prove, not an automatic exemption.
• On a finding of violation, the Department or the Environmental Control Board forwards the respondent's name and address to the IRS, the New York State tax department and the City Department of Finance (28-210.1). An illegal-conversion case is never just a buildings case.

The non-monetary consequences

Where an illegal unit is dangerous - typically a cellar or basement dwelling without proper egress - the Department can order the unit vacated, and the occupants' displacement becomes the owner's emergency. Insurance carriers treat undisclosed conversions as a coverage problem, and a buyer's or lender's diligence will find the open violation in the public record.

Many illegal layouts can never be legalized at all: a cellar unit that cannot meet ceiling-height, light, air and egress requirements has no filing that fixes it. For those, restoration to the approved layout is the only cure, and every day of delay is priced at $1,000 in penalties.

How the violation actually closes

The working sequence for a board or owner is:

• Stop the daily clock first: correct the condition - restore the approved layout, or legalize through a change to the Certificate of Occupancy where the physical conditions genuinely allow it - and file the Certificate of Correction.
• Answer the OATH summons; the daily penalty is imposed at the hearing, and proof of an early correction caps it.
• Pay the imposed penalties and obtain the Administrative Enforcement Unit's approval of the Certificate of Correction (AEU-2).
• Confirm the record shows closed in DOB NOW.

DOB Scan checks DOB NOW and the ECB/OATH records for monitored buildings every day, so an open illegal-conversion violation - and the day it closes - never goes unnoticed. Run a free building check.