ALBANY, N.Y. (AP) – State authorities say they have returned 50,000 improperly deregulated apartments in New York City to rent regulation while restoring more than $2.25 million in overcharged rent to tenants in the last four years.

Homes and Community Renewal says its Tenant Protection Unit in 2012 began tracking down rental apartments in the city that had disappeared from the Office of Rent Administration’s data.

According to the agency, notifying owners who failed to register rent-controlled units since 2009 has resulted in restored tenants’ legal rights and agency rent monitoring for 50,000 apartments.

The unit also used internal data to identify rent overcharges tenants were unaware of, which involved improvements that were never completed or couldn’t be substantiated.