Laws
California ADU laws, explained
What the Government Code says about ADUs, section by section, and what it means for an application.
- State lawADU impact fees and the 750 square foot lineA few square feet can decide whether an ADU owes impact fees at all. The line is drawn at 750, and it is measured in a specific way.Reviewed November 10, 2026
- State lawLegalizing an unpermitted ADU built before 2020If a unit on your property was built without permits before 2020, state law narrows the reasons a city can refuse to permit it now. The protection is real, and it has an edge you need to know about.Reviewed November 10, 2026
- State lawSB 543: what changed for ADU permits in 2026SB 543 didn't change what you can build so much as how your application has to be handled. It also renumbered parts of the code, which is why older guides now point to sections that have moved.Reviewed November 10, 2026