National City, CA Accessory Structures: ADU Rental Restrictions (2026)

Section 18.30.380(G) of the Land Use Code (Title 18) sets the rental rules for accessory dwelling units in National City. An ADU can serve as a rental unit, or it can be occupied by family members, guests, in-home health care providers and others at no cost. The limit is on term: neither the ADU nor the primary dwelling unit can be rented for less than 31 days. ADUs on multi-family properties are subject to the same provision, except that the restriction does not apply to existing multi-family units. An ADU also cannot be sold or otherwise conveyed separate from the primary residence, and owner occupancy of either unit is not required.

The terms are enforced through paperwork before construction. Before a building permit may be issued, the record owner must enter into an agreement with the City in a form approved by the City Attorney. The agreement must provide that the ADU may not be sold or conveyed separately from the primary dwelling unit, that the agreement may be enforced against future purchasers, and that the ADU may not be rented for a period of less than 31 days. The City submits the agreement to the County Recorder for recordation, and it runs with the land for the life of the ADU, so a buyer of the property inherits the same restrictions.

The 31-day floor lines up with the city's short-term rental chapter. Chapter 6.30 defines a short-term rental as a rental for a period of 30 consecutive calendar days or less and states that short-term rentals exclude any accessory dwelling unit permitted under Chapter 18.30.380 and any junior accessory dwelling unit permitted under Chapter 18.30.390. The Land Use Code therefore does not open a vacation-rental path for an ADU; the only rental available is a stay of 31 days or longer. Section 18.30.390 repeats the 31-day term for junior ADUs, adds a residence requirement for the owner, and puts both in the recorded agreement.