California Code, Government Code - GOV § 66452.4

(a) If no action is taken upon a tentative map by an advisory agency that is authorized by local ordinance to approve, conditionally approve, or disapprove the tentative map or by the legislative body within the time limits specified in this chapter or any authorized extension thereof, the tentative map as filed, shall be deemed to be approved, insofar as it complies with other applicable requirements of this division and any local ordinances, and it shall be the duty of the clerk of the legislative body to certify or state his or her approval.

(b) Once a tentative map is deemed approved pursuant to subdivision (a), a subdivider shall be entitled, upon request of the local agency or the legislative body, to receive a written certification of approval.