Junior Accessory Dwelling Units, Explained

Confused about Junior Accessory Dwelling Unit (JADU) requirements, permits, and taxes? We have you covered. Here’s what you need to know about JADU requirements, permits, taxes, and more.

Homeowners are increasingly turning to Junior Accessory Dwelling Units (JADUs) as a way of boosting their property value and income. To help you get a quick handle on these small living units, we’ve broken down the design, rules, and functions that make up a JADU. Plus, a shortcut to simplifying the process of building your own.

What is a Junior Accessory Dwelling Unit?

Located inside a single-family dwelling, a JADU is a habitable space no more than 500 square feet that can be independently rented. These units are only permitted on single-family residences zones with one primary dwelling and within the existing walls of a single-family residence, including attached garages.

JADUs are limited to one per residential lot with a single-family residence. Lots with multiple detached single-family dwellings are not eligible to have JADUs. – Section 65852.22(a)(1)

Additionally, a JADU must:

  • Be on a residential lot where the owner occupies one of the units.
  • Have a separate entrance.
  • Include an efficiency kitchen that provides: a cooking facility with appliances, a food preparation counter, and storage cabinets of reasonable size in relation to the size of the junior accessory dwelling unit.
  • Obtain a Declaration of Restrictions of Occupancy (widely known as a deed restriction) ensuring it would not be sold separately
  • Have access to a bathroom within the primary residence or one inside the unit

How can a JADU be used?

These spaces can serve as an accommodation for visiting relatives and friends or a rental space. As homeowner priorities change, they may be repurposed as a detached home office, gym, studio, and more.

Who can build a JADU?

Homeowners who would live on the same premises as their JADU.

What restrictions are worth noting?

As mentioned above, a Junior Accessory Dwelling Unit cannot exceed 500 square feet.

Do JADUs have their own parking rules?

Additional parking is not required for a JADU.

What are the legal and permit requirements?

Thanks to revised JADU state laws—including Government Code section 65852.22—the permit process has drastically improved. California is no longer allowed to enact strict regulations (e.g., parking rules, floor plan benchmarks) or take longer than 60 days to review an application. JADU services like YimbyLA can offer an expedited building experience by managing the paperwork, red tape, and logistics for property owners.

How does adding a JADU affect property value and taxes?

Similar to home remodeling assessments that occur after adding square footage, building a Junior Accessory Dwelling Unit triggers a reassessment. California’s Proposition 13 bases this amount on renovation or addition costs, not a property’s new market value. The revaluation is then added to the existing property assessment.

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