Certificate of no harassment

A certificate of no harassment is the clearance certain buildings must obtain before alteration or demolition permits: the owner must demonstrate that tenants were not harassed during the lookback period, with the housing agency investigating and neighbors heard. The requirement attaches to defined categories — single-room-occupancy stock prominently, plus buildings in covered programs and districts — and denial blocks the permits.

The mechanism exists because displacement pressure precedes redevelopment: the certificate makes a building's treatment of its tenants a documented precondition to profiting from their absence. In records, CONH applications, grants, and denials are part of both the building's permit history and its tenant-relations record.