Butte County, CA Accessory Structures: ADU Impact Fees (2026)

22. 3 sets the impact fee rule directly: a local agency, special district or water corporation cannot impose any impact fee on an ADU or JADU under 750 square feet, and for units at or above that threshold the fee must be charged proportionately to the square footage of the primary dwelling unit rather than as a flat charge. The section cross-references Government Code Section 66323 for additional state-law restrictions on ADU impact fees beyond this proportionality rule. The fee waiver sits alongside other D-subsection site rules: ADUs and JADUs must be on legally created parcels, are treated as an accessory use that does not count against the parcel's allowable density, and are deemed a residential use consistent with the existing general plan and zoning designation, meaning a qualifying ADU does not need a separate land use entitlement beyond the building permit contemplated in Subsection B.

Guest houses are carved out of this section's requirements entirely and instead regulated under Section 24-156(g). This fee treatment is distinct from the parking and setback standards found in Subsection G of the same section, and from the impact fee exemption for the primary dwelling itself, which is a separate policy question the state statute and this local section address only for the accessory unit.