The mayor's office, the Department of Housing Preservation and Development and the Department of Finance are threatening to suspend tax benefits for some owners of apartments that are part of the 421-a program if those apartments are found to not be in compliance with the program's requirements.

The mayor and the commissioners of the two city agencies said in a press release that the city's Department of Finance sent warning letters to owners of more than 3,000 buildings in the program that contain more than 37,000 apartments.

According to the city, the owners being targeted have received 421-a benefits but have not filed a Final Certificate of Eligibility with the Department of Finance. The city says the tax exemptions for the buildings will be suspended if the certificates are not filed.

Section 421-a of the state's Real Property Tax Law provides a partial city tax exemption for newly constructed multi-family residential buildings for at least 10 years.

The city says the owners of the buildings in question would have paid more than $300 million in taxes this year alone if they were not getting 421-a benefits.