Introduction New York City homeowners and tenants often assume that kitchen or bath upgrades follow the same rules across all apartments. In reality, they don’t. A co-op in Park Slope or SoHo  might only approve renovations once a managing agent signs off on insurance and DOB filings, while a rent-stabilized unit in Harlem or Astoria  can’t even change fixtures without HPD review. By understanding which filings apply — Alt-1 vs Alt-2, licensed trade work, or simple cosmetic

If your approval stalls, labor and elevator reservations slip. In NYC co-ops and condos, one missing checkbox can push a start date by 2–3 weeks. This guide breaks the top filing mistakes we still see across Harlem, UWS, Astoria, and Brooklyn Heights, and shows how to avoid them. It is written for owners, boards, and design teams who want predictable schedules.