Gov. Code, § 66451.19

(a) Except as provided in Sections 66451.195, 66451.301, and 66451.302, a city or county shall no later than January 1, 1986, record a notice of merger for any parcel merged prior to January 1, 1984. After January 1, 1986, no parcel merged prior to January 1, 1984, shall be considered merged unless a notice of merger has been recorded prior to January 1, 1986.

(b) Notwithstanding the provisions of Sections 66451.12 to 66451.18, inclusive, a city or county having a merger ordinance in existence on January 1, 1984, may, until July 1, 1984, continue to effect the merger of parcels pursuant to that ordinance, unless the parcels would be deemed not to have merged pursuant to the criteria specified in Section 66451.30. The local agency shall record a notice of merger for any parcels merged pursuant to that ordinance.

(c) At least 30 days prior to recording a notice of merger pursuant to subdivision (a) or (b), the local agency shall advise the owner of the affected parcels, in writing, of the intention to record the notice and specify a time, date, and place at which the owner may present evidence to the legislative body or advisory agency as to why the notice should not be recorded.

(d) The failure of a local agency to comply with the requirements of this article for the merger of contiguous parcels or units of land held in common ownership shall render void and ineffective any resulting merger or recorded notice of merger and no further proceedings under the provisions of this division or a local ordinance enacted pursuant thereto shall be required for the purpose of sale, lease, or financing of those contiguous parcels or units, or any of them, until such time as the parcels or units of land have been lawfully merged by subsequent proceedings initiated by the local agency which meet the requirements of this article.

(e) The failure of a local agency to comply with the requirements of any prior law establishing requirements for the merger of contiguous parcels or units of land held in common ownership, shall render voidable any resulting merger or recorded notice of merger. From and after the date the local agency determines that its actions did not comply with the prior law, or a court enters a judgment declaring that the actions of the agency did not comply with the prior law, no further proceedings under the provisions of this division or a local ordinance enacted pursuant thereto shall be required for the purpose of sale, lease, or financing of such contiguous parcels or units, or any of them, until such time as the parcels or units of land have been lawfully merged by subsequent proceedings initiated by the local agency which meet the requirements of this article.