What changes in ADU law should I know about for 2025-2026?

California's ADU laws are revised almost every legislative session, and the 2025-2026 window brought several meaningful changes affecting timelines, occupancy, legalization, unit counts, and the energy code. Here is what matters most for a homeowner, contractor, or designer planning a project in this period.

Key statutory changes

• AB 1332 (enacted 2025) — pre-approved plans. Every California city must maintain a library of pre-approved ADU plans. Applications using a pre-approved plan must be approved or denied within 30 days, versus 60 days for a custom design. This is a fast track for homeowners willing to build from a standard design.
• AB 976 (permanent, effective 2024) — no owner-occupancy for ADUs. The owner-occupancy requirement for standard ADUs is permanently eliminated, so you can rent out both the main house and the ADU without living on the property. Note that JADUs still require owner occupancy.
• AB 2533 (2025) — amnesty / legalization. Creates a pathway to legalize unpermitted ADUs built before 2020. Cities cannot deny these permits based on building-standard violations alone unless a severe safety hazard exists.
• SB 1211 (enacted 2025) — more units on multifamily lots. Allows up to eight detached ADUs on qualifying multifamily lots, subject to conditions. Verify applicability with your jurisdiction.
• SB 543 (effective January 1, 2026) — 15-day completeness clock. The city must notify you of any missing application items within 15 business days; miss that window and the application is deemed complete by operation of law.

The 2025 Energy Code (Title 24, Part 6)

The 2025 California Energy Code applies to ADU permit applications submitted on or after January 1, 2026, and it reshapes mechanical and electrical design:

• Heat pumps become the prescriptive baseline for space conditioning and water heating, making all-electric designs the path of least resistance.
• Expanded HERS verification — refrigerant charge verification across all 16 climate zones and tighter duct leakage limits.
• Battery / energy-storage readiness (ESS-ready) provisions for new detached ADUs.
• Higher insulation and envelope minimums across most climate zones.

This means a CF1R prepared under the prior code cycle will be rejected for a permit filed on or after the effective date — your Title 24 report must be on the current cycle.

What this means for your project

The through-line of these reforms is clear: faster approvals, fewer occupancy strings, and a strong push toward all-electric, heat-pump-based design.

ADU law changes every session and details vary by jurisdiction — confirm the current rules and effective dates with your local building department before relying on any single provision. To make sure your MEP and energy documents reflect the current code, see our Full MEP Package with the Title 24 add-on, or read the California ADU requirements page.