ADU & basement guide
Legalize your basement apartment or backyard cottage under NYC Local Laws 126/127. Grants may be available.
💰 NYC ATR grants available
Up to $120,000 in funding for qualifying basement conversions through the Accessory Transformation Program.
Check eligibility
Confirm your property is in a qualifying zone under Local Law 126/127. Most 1-4 family homes in NYC are eligible.
Get a professional assessment
Hire a licensed architect or engineer to evaluate your basement or accessory space for code compliance.
Apply for ATR certification
Submit your application to the NYC Department of Buildings Accessory Transformation Program (ATR).
Complete renovations
Make required safety upgrades: egress windows, ceiling height, fire separation, and proper ventilation.
Obtain Certificate of Occupancy
After passing inspection, receive your updated C of O and list your legal unit on PropertyOwnersNYC.