· State law
SB 1117 signed: from 2027, ADU impact fees can only be charged on the area over 750 sq ft
The Governor approved SB 1117 (Chapter 809, Statutes of 2026) on September 29, 2026. It amends Gov. Code 66311.5: on lots with up to two ADUs, impact fees on an ADU over 750 sq ft must still be proportional to the primary home, and may only be charged on the area over 750 sq ft. Regular 2026 statutes take effect January 1, 2027. Until then, fees on a larger ADU are figured on its full size. Our calculator has a 2027 setting that shows the difference.
This bill would require the charge for certain accessory dwelling units to be based only on the area in excess of 750 square feet of interior livable space.
Added Oct 18, 2026.