Fullerton, CA Accessory Structures: ADU Impact Fees (2026)

100(C)(2) sets the impact fee structure required by Cal. : no impact fee is imposed on any ADU smaller than 750 square feet, and for ADUs at or above that threshold the fee must be charged proportionately to the primary dwelling's square footage rather than as a flat fee. All applicable public service and recreation impact fees are due before occupancy. Section (C)(2)(d) ties the definition of IMPACT FEE to Cal. Gov't Code § 66324. 100(C)(3) governs connection fees and capacity charges: an ADU is not treated as a new residential use for water or sewer connection fee purposes unless it is being built together with a new single-family dwelling.

An ADU contained within a proposed or existing single-family home that meets the interior-conversion standard in (H)(1)(a) pays no connection fee or capacity charge at all (again, unless built with a new single-family home); all other ADUs pay a connection fee or capacity charge scaled to the unit's size or number of plumbing fixtures. A JADU is never treated as a separate or new dwelling unit for water, sewer, or power purposes under (C)(3)(c).