Alameda County Tax Assessor's (December Newsletter) Important ADU Information

Dear Alameda County Residents, Happy Holidays! As we enter this festive season and prepare to close out the year, I want to extend my warmest wishes to you and your families. This month, our office proudly supported both Supervisor David Haubert's (District 1) and Supervisor Elisa Márquez's (District 2) Holiday Food & Toy Drives. These events bring together neighbors, volunteers, and community partners to support families across Alameda County, and we are grateful to the organizers, sponsors, and everyone who donated to make a meaningful difference for children and families in need. As we celebrate the many holidays observed throughout December, I wish you a warm and joyful season—whether you are honoring Hanukkah, Christmas, Kwanzaa, or simply welcoming the hope and possibilities of the new year. From all of us at the Alameda County Assessor's Office, thank you for allowing us to serve you. We look forward to continuing to serve you in the year ahead.  Sincerely, Phong La Alameda County Assessor Assessory Dwelling Units What is an Accessory Dwelling Unit (ADUs)?  An Accessory Dwelling Unit, or "ADU," is a secondary dwelling unit that is either attached to or detached and located on the same lot as an existing dwelling unit or located within the living area of an existing dwelling. An ADU can only be with a single-family residence and cannot be additional to a multi-family unit.   Since 2017, California has updated ADU laws to reduce building barriers, streamline approvals, and expand housing options, and Alameda County follows these statewide standards.  Current State Standards for ADUs The property must be zoned for single-family or multi-family use and have an existing single-family home.  An ADU can be attached, inside the existing home, or detached on the same lot. Attached ADUs may add up to 50% more living area, not to exceed 1,200 square feet.  The ADU is not intended for sale, separate from the primary residence, and may be rented.  Passageways are not required when building an ADU.  Garage conversions do not require setbacks, and ADUs built above a garage may have side and rear setbacks as small as five feet.  Parking requirements are limited to one space per unit or bedroom, and tandem parking on the driveway is allowed.  ADUs must meet all local building code requirements.  Approval from the local health officer is required when a private sewage disposal system is used.  What is a Junior Accessory Dwelling Unit (JADU)?  A JADU is similar to an ADU but must not exceed 500 square feet and must be completely contained within the space of an existing residential structure. JADU Standards: Only one JADU is allowed per residential parcel with an existing single-family home.  The property must be owner-occupied, either in the main home or the JADU.  A recorded deed restriction is required, stating the JADU cannot be sold separately and must follow all size and use rules.  A JADU must be fully within the existing home and have its own entrance as well as interior access.  A JADU must include an efficiency kitchen (sink, cooking appliance, counter, and storage) that meets building code standards; no gas or 220v appliances are allowed.  A JADU may share the main home's bathroom.  No additional parking is required.  No extra fees are charged for water, sewer, or power connections.  ADU and JADU permits will follow existing rules and notes about the units should be included in building plans until new guidelines are available.   How are ADUs assessed for property tax purposes California law requires most property to be assessed based on its market value. For ADUs, the Sales Comparison Approach would normally be used, but because ADUs are often new and comparable sales are limited, the Cost Approach is typically applied.  Under the Cost Approach, the assessment reflects the total cost to build the ADU—this includes labor, materials, contractor overhead, permits, inspections, design and architectural fees, construction insurance, and other expenses needed to complete the project.  Does major work on the main home to build an ADU trigger a reassessment of the main home? Assessable new construction includes major changes that make part of a home essentially new or change how that part is used. The value added is based on market value and is added to the home's existing assessment.  If you're considering building an ADU or JADU, our office is here to help you understand how it may affect your property assessment.  Visit us at County Administration Building 1221 Oak Street, Room 145, Oakland (During normal business hours) or call: (510) 272-3787. Visit the Assessor's Office website for additional information. Alameda County Historic Spotlight Union City's Alvarado: The Cradle of America's Sugar Boom  Before the Alvarado area was incorporated into Union City, the small town was a largely rural community, consisting of small farmers. Eventually, it became one of the few domestic sugar manufacturers in America. The potential for Alvarado was not initially realized until a man named Ebenezer H. Dyer moved to Alameda County in 1860. Dyer was a pioneering figure in Alameda County, bringing vision, innovation, and perseverance to the region's agricultural and industrial growth. After arriving in California to assist his brother's farm operations, Dyer became Alameda County's surveyor and later a U.S. Deputy Surveyor for the state. His real legacy, however, was sparked by his fascination with sugar beet cultivation.  In the late 1860s, Dyer began experimenting with beet sugar production on his Alvarado farm, leading to the formation of the California Beet Sugar Company. In 1870, this company produced the first commercial sugar from beets in the United States, placing Alvarado (now part of Union City) at the forefront of a new American industry.  Despite early setbacks, including disagreements with German technicians and economic challenges from sugar price wars, Dyer remained committed to the beet sugar enterprise. He and his family went on to establish several sugar companies, including the successful Standard Sugar Manufacturing Company and later the Pacific Coast Sugar Company. These ventures laid the groundwork for the beet sugar industry in California and beyond. Over the decades, the original Alvarado plant weathered closures, equipment failures, and crop losses—but also saw innovation and revival, especially during wartime. Ultimately, the plant was rebuilt and modernized by the Holly Sugar Corporation in the 1930s and continued operations until 1969, standing as a testament to Dyer's legacy and the lasting impact of his pioneering spirit.  Got a Question About Your Property Taxes? The next Property Transfer Legal Clinic will take place on Friday, December, 19. Please click below to make an appointment with a volunteer attorney for a free 30-minute consultation. Get the Latest—Follow Us on Instagram & Facebook

Alameda County Assessor's Office | 1221 Oak Street, Room 145 | Oakland, CA 94612 US