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

Section XIII-C.10.030.D.3 requires payment of all applicable fees before a Building Permit issues for an ADU or JADU, but it carves out a specific exemption: no impact fee applies to any JADU or to an ADU under 750 square feet, regardless of whether the unit is attached or detached. For ADUs of 750 square feet or more, the impact fee is prorated using the ADU's floor area divided by the primary dwelling's floor area, multiplied by the typical fee charged for a new dwelling, rather than a flat per-unit charge.

The section defines 'impact fee' by reference to Government Code sections 66000(b) and 66477, and expressly excludes any water or sewer connection fee or capacity charge from that definition, so the fee exemption for small ADUs and JADUs never reaches utility hookup costs. Utility connections are handled separately: if an ADU or JADU is built along with a new single-family home, a separate direct utility connection and the normal connection fee and capacity charge for a new dwelling are required. An ADU built within an existing structure does not need a new direct utility connection, while an ADU not within an existing structure must install one and pay a connection fee or capacity charge sized to its burden on the water or sewer system, based on unit size or plumbing fixture count.