Boulder, CO Accessory Structures: ADU Rental Restrictions (2026)

C. 1981. " Section 4-20-18, "Rental License Fee," sets that fee at $190 per accessory dwelling unit and adds a $250 fee for any investigative inspection the city manager performs to check compliance. Short-term rental of the ADU, or of the principal dwelling on a lot that also has an ADU, is flatly prohibited unless the owner obtains authorization under Section 10-3-19, "Short-Term Rentals," which requires its own annual certification and fee. The code also bars splitting ownership of the ADU from the house: no person may convey the accessory dwelling unit independently of the principal dwelling on the lot or parcel, so an ADU can never become a separately deeded condo-style unit.

The ADU must keep the same utility hookups and meters as the principal dwelling unless the city approves a separate connection under the City of Boulder Design and Construction Standards. Owners of an affordable ADU must also record a declaration of use with the Boulder County Clerk and Recorder certifying the affordability standard and bedroom count. Any prior planned development, planned unit development, or site review condition that tried to prohibit ADUs on a property is void and unenforceable once the ADU meets these current standards, and establishing one on such a property goes through the minor modification process instead of a full amendment.