Smithtown, NY Accessory Structures: ADU Rental Restrictions (2026)

Section 322-82C(23)(f) restricts where an accessory apartment dwelling unit can exist at all: it may only be permitted on premises containing a retail store or shop, personal shop, office, bank, funeral home, restaurant, tavern, bar, inn, or a shop for custom work and making articles sold on the premises. That list excludes ordinary single-family residential premises entirely, so the rental right is tied to a commercial host use, not to residential zoning generally. Subsection (g) then caps how long that rental right lasts: Board of Appeals permission for the accessory apartment is granted for an initial three-year period, renewable every three years, and the Board reinspects for continued compliance with all the requirements before each renewal.

The property owner must record a covenant with the Board of Appeals agreeing to remove the residential use once the permit terminates, and if the owner fails to file a renewal application within 60 days after the three-year term ends, the permission automatically terminates with no further action needed by the Town. That automatic-termination structure means an accessory apartment's rental status can lapse purely through inaction, converting what looks like an established rental into an unlawful use overnight if the owner misses the filing window; the tenant then has to vacate and the owner must remove the second kitchen or other residential improvements identified in the recorded covenant.