California’s AB 68, signed in 2019 and effective January 1, 2020, rewrote the rules for building an accessory dwelling unit by stripping cities of most of the discretion they had used to slow projects down. Under the California AB 68 ADU law, local agencies must approve a complete application within 60 days using objective standards only, cannot force ADUs below certain size and height floors, cannot demand parking in a long list of common situations, and cannot require the owner to live on the property. The legislature has amended the framework every year since, so what follows is AB 68 as passed and what the rules look like now.
What AB 68 Actually Changed
Before AB 68, cities had 120 days to act on an ADU permit and could apply subjective design review. The law replaced that with a ministerial process: no hearing, no discretionary review, and a 60-day clock on completed applications for lots with an existing dwelling.1California Legislative Information. California Government Code 65852.2 If the agency denies the application, it has to return a written list of every deficiency and explain how to fix each one, all within that same window. That prevents the older pattern where a city rejects on one ground, the homeowner fixes it, and the city then finds something new.
If a city fails to adopt a compliant ADU ordinance, state standards apply directly and the local rules become unenforceable. The California Department of Housing and Community Development reviews local ordinances and issues findings letters when cities fall short.
On a single-family lot, state law allows one ADU and one junior accessory dwelling unit (JADU). A JADU is a smaller unit, up to 500 square feet, built entirely within the walls of an existing or proposed single-family home, with its own entrance and at least an efficiency kitchen.2California Legislative Information. California Government Code 65852.22
Size Floors Your City Cannot Undercut
AB 68 barred local ordinances from blocking construction of at least an 800-square-foot ADU.3California Legislative Information. AB 68 – Land Use: Accessory Dwelling Units Companion legislation raised the floor further: a city cannot cap a detached ADU below 850 square feet for a studio or one-bedroom, or below 1,000 square feet for a unit with two or more bedrooms.
Attached ADUs work on a percentage rule. An attached unit can be up to 50 percent of the primary home’s existing living area, with an overall cap of 1,200 square feet applying to detached units. A homeowner converting part of a 1,600-square-foot house could build an 800-square-foot attached ADU. Someone putting a freestanding cottage in the backyard can go up to 1,200 square feet regardless of the main home’s size.
Height and Setback Minimums
AB 68 set a 16-foot minimum height allowance for detached ADUs and capped side and rear setbacks at four feet.4California State Assembly. Assembly Committee on Local Government AB 68 Analysis A city can be more permissive; it cannot force you shorter than 16 feet or farther than four feet from those lot lines.
Later legislation added higher tiers on top of the AB 68 baseline:5California Department of Housing and Community Development. Accessory Dwelling Unit Handbook
- 16 feet is the base height for any detached ADU.
- 18 feet is allowed if the lot is within half a mile of a major transit stop or high-quality transit corridor, with two extra feet permitted to match the primary home’s roof pitch. The 18-foot allowance also applies on lots with an existing or proposed multistory multifamily building.
- 25 feet applies to attached ADUs, or the height limit that applies to the primary dwelling under local zoning, whichever is lower.
Cities also cannot require setback modifications for ADUs built within existing structures, and they cannot impose front setback rules that would prevent an 800-square-foot unit with four-foot side and rear setbacks.
Parking Exemptions
Parking requirements had killed many ADU projects before 2020. Under current law, a local agency cannot require any parking for an ADU in these situations:5California Department of Housing and Community Development. Accessory Dwelling Unit Handbook
- The ADU is within half a mile walking distance of public transit.
- The ADU is in an architecturally and historically significant historic district.
- The ADU is part of the existing primary residence or an accessory structure like a converted garage.
- On-street parking permits are required in the area but are not offered to the ADU occupant.
- A car share vehicle is located within one block.
- The ADU permit is submitted with a permit for a new primary dwelling on the same lot, provided one of the other exemptions also applies.
Where parking is required, it cannot exceed one space per unit or per bedroom. And if you demolish a garage, carport, or uncovered parking space to build the ADU, the city cannot make you replace those lost spaces.
Fees and Sprinklers
Development fees used to be one of the largest barriers to ADU construction. Under current law, ADUs of 750 square feet or less are exempt from impact fees entirely. JADUs of 500 square feet or less get the same exemption. For ADUs over 750 square feet, impact fees must be charged proportionately based on the ADU’s square footage relative to the primary dwelling, not at the full rate a new single-family home would trigger.5California Department of Housing and Community Development. Accessory Dwelling Unit Handbook
Adding an ADU does not trigger a fire sprinkler requirement for the main house. If your existing home lacks sprinklers and you add an attached ADU, the city cannot force you to retrofit the primary residence.
Owner-Occupancy Rules
AB 68 suspended local owner-occupancy requirements from January 1, 2020, through January 1, 2025. During that window, homeowners could rent out both the main home and the ADU without living on-site. In 2023, AB 976 made that prohibition permanent for standard ADUs.6California State Assembly. AB 976 (Ting) – Assembly Bill Policy Committee Analysis Cities can no longer require you to live on the property as a condition of an ADU permit.
JADUs are different. A JADU still carries an owner-occupancy requirement: the property owner must live in either the main portion of the home or the JADU itself. Government agencies, land trusts, and housing organizations that own the property are exempt.2California Legislative Information. California Government Code 65852.22
HOA Rules Cannot Block You
If your property is in a homeowners association, the HOA cannot stop the project outright. California Civil Code Section 4751 voids any covenant, deed restriction, or HOA governing document that effectively prohibits or unreasonably restricts an ADU or JADU on a single-family lot that otherwise meets state requirements. That reaches CC&Rs, architectural review board rules, and any other HOA-imposed restriction.
HOAs can still enforce what the statute calls “reasonable restrictions.” A rule that your ADU match the exterior paint color of the main house is probably reasonable. A rule requiring custom materials that double your construction costs likely is not, because a restriction is unreasonable if it makes the unit so expensive that it effectively prevents construction or extinguishes your ability to build a unit that would otherwise comply with state law.
What AB 68 Did Not Cover
AB 68 was the starting point, not the finish line. Height increases came later through AB 2221 and SB 897, effective in 2023. The permanent owner-occupancy fix came through AB 976, effective in 2024. AB 1033, also effective in 2024, lets cities adopt local ordinances allowing an ADU to be sold separately from the primary home as a condominium; that option is not statewide and depends on whether your city has opted in.5California Department of Housing and Community Development. Accessory Dwelling Unit Handbook JADUs cannot be sold separately in any circumstance.
AB 68 also applies beyond single-family lots. On a lot with an existing multifamily building, state law requires local agencies to allow at least one conversion ADU within the existing building and up to 25 percent of the existing units, plus up to eight detached ADUs (capped at the number of existing units on the lot). JADUs are single-family only.
Where the Statute Lives Now
The underlying code sections were recodified. What was Government Code Section 65852.2 now appears at Sections 66314 through 66323, and JADU provisions moved from Section 65852.22 to Section 66333. The rules did not change in the recodification, only the numbering. A local ordinance that still cites the old sections is not necessarily out of date on substance, but HCD’s current handbook and any legislation from 2024 forward use the new numbers.