California Code, Government Code - GOV § 66457

(a) A final map or parcel map conforming to the approved or conditionally approved tentative map, if any, may be filed with the legislative body for approval after all required certificates or statements on the map have been signed and, where necessary, acknowledged.

(b) If the subdivision lies entirely within the territory of a city, the map shall be filed with the city.  If the subdivision lies entirely within unincorporated territory, the map shall be filed with the county.  If the subdivision lies partially within two or more territories, the map shall be filed with each, and each shall act thereon as provided in this chapter.