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

180 of the Orange Municipal Code sets the City's impact fee policy for accessory dwelling units. Units under 750 square feet owe no impact fees at all, removing what is often one of the largest cost barriers to building a small backyard unit or converting existing space. Once an ADU reaches 750 square feet or more, the City still charges impact fees, but calculates them proportionately based on the ADU's square footage compared to the primary dwelling unit on the same lot, rather than applying the flat per-unit fee schedule used for a newly constructed single-family home.

050(A)(2), every JADU falls automatically within the fee-exempt threshold. This proportional approach means a homeowner adding a modest 900-square-foot ADU behind a large primary residence pays a smaller share of citywide impact fees than the fee charged for a comparably sized standalone home, since the calculation is tied to the ADU's size relative to the existing structure rather than to a countywide flat schedule.