California Code, Government Code - GOV § 66499.20.2

Subdivided lands may be merged and resubdivided without reverting to acreage by complying with all the applicable requirements for the subdivision of land as provided by this division and any local ordinances adopted pursuant thereto.  The filing of the final map or parcel map shall constitute legal merging of the separate parcels into one parcel and the resubdivision of such parcel, and the real property shall thereafter be shown with the new lot or parcel boundaries on the assessment roll.  Any unused fees or deposits previously made pursuant to this division pertaining to the property shall be credited pro rata towards any requirements for the same purposes which are applicable at the time of resubdivision.  Any public streets or public easements to be left in effect after the resubdivision shall be adequately delineated on the map.  After approval of the merger and resubdivision by the governing body or advisory agency the map shall be delivered to the county recorder.  The filing of the map shall constitute legal merger and resubdivision of the land affected thereby, and shall also constitute abandonment of all public streets and public easements not shown on the map, provided that a written notation of each abandonment is listed by reference to the recording data creating these public streets or public easements, and certified to on the map by the clerk of the legislative body or the designee of the legislative body approving the map.