Gov. Code, § 66424.6

(a) When a subdivision, as defined in Section 66424, is of a portion of any unit or units of improved or unimproved land, the subdivider may designate as a remainder that portion which is not divided for the purpose of sale, lease, or financing. Alternatively, the subdivider may omit entirely that portion of any unit of improved or unimproved land which is not divided for the purpose of sale, lease, or financing. If the subdivider elects to designate a remainder, the following requirements shall apply:

(1) The designated remainder shall not be counted as a parcel for the purpose of determining whether a parcel or final map is required.

(2) For a designated remainder parcel described in this subdivision, the fulfillment of construction requirements for improvements, including the payment of fees associated with any deferred improvements, shall not be required until a permit or other grant of approval for development of the remainder parcel is issued by the local agency or, where provided by local ordinance, until the construction of the improvements, including the payment of fees associated with any deferred improvements, is required pursuant to an agreement between the subdivider and the local agency. In the absence of that agreement, a local agency may require fulfillment of the construction requirements, including the payment of fees associated with any deferred improvements, within a reasonable time following approval of the final map and prior to the issuance of a permit or other grant of approval for the development of a remainder parcel upon a finding by the local agency that fulfillment of the construction requirements is necessary for reasons of:

(A) The public health and safety; or

(B) The required construction is a necessary prerequisite to the orderly development of the surrounding area.

(b) If the subdivider elects to omit all or a portion of any unit of improved or unimproved land which is not divided for the purpose of sale, lease, or financing, the omitted portion shall not be counted as a parcel for purposes of determining whether a parcel or final map is required, and the fulfillment of construction requirements for offsite improvements, including the payment of fees associated with any deferred improvements, shall not be required until a permit or other grant of approval for development is issued on the omitted parcel, except where allowed pursuant to paragraph (2) of subdivision (a).

(c) The provisions of subdivisions (a) and (b) providing for deferral of the payment of fees associated with any deferred improvements shall not apply if the designated remainder or omitted parcel is included within the boundaries of a benefit assessment district or community facilities district.

(d) A designated remainder or any omitted parcel may subsequently be sold without any further requirement of the filing of a parcel map or final map, but the local agency may require a certificate of compliance or conditional certificate of compliance.