As of March 6, 2026, the best starting point is the California HCD ADU Handbook page, which now points readers to a 2026 addendum summarizing the state law changes in effect on January 1, 2026. That matters because many city websites still lag the current statewide baseline.

Bottom line: if a local handout or planner says “our city does not allow that,” compare it against current state law first. California’s ADU rules still preempt many local restrictions.

The 2025 Title 24 building code cycle is now in effect

The California Building Standards Commission states that the 2025 California Building Standards Code, Title 24, became effective on January 1, 2026. For ADU owners, that means your design team, plan set, and permit review now need to track the current code cycle, not the 2022 cycle that applied through December 31, 2025.

In practice, homeowners should expect 2026 permit sets to be reviewed under current structural, energy, plumbing, mechanical, and green-building requirements. That does not erase ADU streamlining rules, but it does affect how compliant plans are prepared and checked.

SB 1211 changed the statewide ADU baseline in a meaningful way

SB 1211, chaptered on September 19, 2024, is one of the biggest reasons the statewide ADU map looks different in 2026.

  • It bars cities from imposing unauthorized objective standards on ADU projects that qualify for ministerial approval.
  • It expands detached ADU capacity on lots with existing multifamily housing from two to as many as eight, as long as the number does not exceed the number of existing units on the lot.
  • It also says uncovered parking spaces demolished or converted with an ADU do not have to be replaced.

For homeowners and small property owners, the practical takeaway is simple: some multifamily lots now have materially more ADU potential than they did before, and local design review has less room to add extra hurdles where state law already spells out the approval path.

ADU owner-occupancy restrictions remain off the table

AB 976 is still a major 2026 issue because it continues to protect homeowners from local ADU owner-occupancy mandates. The bill states that local agencies may not impose an owner-occupancy requirement on ADUs.

That matters for flexibility. If you are planning an ADU for family use now and long-term rental later, or you may move and keep the property as an investment, that statewide rule continues to support those choices.

AB 2533 gives older unpermitted units a stronger legalization path

AB 2533 remains highly relevant in 2026 because it expanded protections for unpermitted ADUs and JADUs built before January 1, 2020.

  • Local agencies generally cannot deny permits for those older units over zoning or building-standard issues unless corrections are necessary to address conditions that would make the building substandard.
  • Cities must inform the public about the program and provide more transparency around substandard conditions.
  • Impact fees and connection or capacity charges are also limited except in specified circumstances.

If you bought a property with a garage conversion, backyard unit, or internal apartment that was never fully legalized, 2026 is still a strong time to evaluate whether that unit qualifies for the AB 2533 pathway.

JADU rules shifted again for 2026

The newest change in the mix is AB 1154, approved October 10, 2025 and effective in 2026. It narrows when owner-occupancy can be required for a JADU.

  • If the JADU shares sanitation facilities with the main home, owner-occupancy can still be required.
  • If the JADU has separate sanitation facilities, owner-occupancy is not required.
  • The statute also requires JADU rentals to be for terms longer than 30 days.

That is a targeted but meaningful change. It makes some JADU configurations more useful to owners who want a small independent unit without tying permanent owner occupancy to the lot.

What homeowners should do in 2026

If you are actively planning a project, 2026 is a good year to be more disciplined than ever about intake and due diligence:

  • Ask your city for its current ADU handout and compare it to the state sources above.
  • Confirm your architect, designer, or contractor is preparing plans to the 2025 Title 24 cycle now in effect.
  • If you own multifamily property, revisit detached ADU capacity under SB 1211. The site may pencil differently than it did a year ago.
  • If you have an older unpermitted unit, get a focused legalization review instead of assuming it cannot be saved.

California ADU law is now mature enough that the biggest mistakes are usually procedural: relying on stale local summaries, designing to the wrong code cycle, or assuming a prior “no” from a city is still valid under the current state framework.

For homeowners who want to go deeper, start with the HCD ADU Handbook and 2026 addendum, then confirm project-specific code requirements through the current Title 24 materials.