How Tentative Maps Work Under the Subdivision Map Act

A tentative map is the first formal application a California landowner files under the Subdivision Map Act to divide property into five or more parcels. It shows the proposed layout, streets, utilities, grading, and existing conditions so the local planning agency can decide whether to approve, condition, or deny the subdivision. Approval is conditional and time-limited: the developer still has to record a final map before the tentative map expires, or the whole process starts over.

When You Need a Tentative Map

Government Code Section 66426 requires the tentative-and-final-map process for any subdivision creating five or more parcels, five or more condominium units, a community apartment project with five or more parcels, or the conversion of an existing building into a stock cooperative with five or more dwelling units.¹ Splits that create four or fewer parcels use the simpler parcel map process instead.

Section 66426 also lets some larger subdivisions skip the tentative map and use a parcel map when the project fits one of these categories:

The original parcel is under five acres, every new lot fronts a maintained public street, and no dedications or new improvements are required.
Every resulting parcel is at least 20 acres with approved access to a public street.
The land is already zoned commercial or industrial, has approved street alignments, and fronts a public street.
Every resulting lot is at least 40 acres or a quarter-quarter section.

The exemption removes the tentative map requirement but not the mapping requirement itself. A parcel map is still needed.¹

What the Map Has to Show

The statute defines a tentative map as a document showing the design and improvements of a proposed subdivision and the existing conditions in and around it, and it explicitly says the map does not need to be based on a detailed final survey.² Specific content requirements come from local ordinances, but nearly every jurisdiction expects the same core information:

Proposed street locations, widths, grades, and connections to existing public streets.
Each lot’s boundaries, area, numbering, and intended use, showing compliance with zoning minimums.
Topography and grading data showing how runoff will be handled without pushing water onto neighboring properties.
Locations of sewer, water, storm drain, and utility easements.
The name of the subdivider, the project engineer or surveyor, and a statement of intended use.

A boundary survey prepared by a licensed land surveyor or civil engineer establishes the legal perimeter. The map itself doesn’t need final-survey precision, but the boundary survey underlying it does. Most agencies also ask for a preliminary title report so staff can catch existing easements or encumbrances that would conflict with the proposed layout.

Environmental Review

Every tentative map application triggers review under the California Environmental Quality Act. Planning staff usually begin with an initial study. If it finds no significant environmental impacts, the agency prepares a negative declaration. If impacts exist but can be reduced to a less-than-significant level through specific measures, a mitigated negative declaration is used. Projects with unavoidable significant impacts require a full environmental impact report, which is far longer and more expensive.

Review covers traffic, noise, air quality, biological resources, water supply, and other categories relevant to the site. Inadequate CEQA analysis is one of the most common reasons a tentative map stalls or gets denied.

Subdivisions near waterways or wetlands may also need a federal permit under Section 404 of the Clean Water Act before discharging fill material into jurisdictional waters.³ Sites with protected species habitat can trigger a federal incidental take permit and a conservation plan showing how impacts will be minimized and mitigated.⁴ These run parallel to local approval and can add months to the timeline.

How the Approval Process Works

After a complete application is submitted, the local agency provides public notice of any hearing on the map under the general notice provisions in Government Code Sections 65090 and 65091. Neighbors and other interested parties can review the layout and testify.

The advisory agency or planning commission has 50 days after the map is filed to approve, conditionally approve, or deny it.⁵ The 50-day clock can be extended by mutual agreement between the developer and the agency, which happens often when environmental review or design revisions run long.

The developer or any interested person can appeal. Appeals go to the local legislative body, usually the city council or board of supervisors, which holds its own hearing and issues a decision within 10 days after the hearing closes. If no one appeals within the locally prescribed window, the advisory agency’s decision becomes final.

Grounds an Agency Can Cite for Denial

The Map Act limits local discretion by listing the specific findings that justify denial. Under Section 66474, an agency must deny a tentative map if it finds any of the following:⁶

The map does not conform to the applicable general plan or specific plan.
The design or proposed improvements conflict with general or specific plan requirements.
The site cannot physically support the type of development proposed.
The site cannot physically support the proposed number of units.
The design or improvements would cause substantial environmental damage or avoidably injure fish, wildlife, or habitat.
The design or improvements would cause serious public health problems.
The project would interfere with public easements for access through or use of the property, unless the developer provides substantially equivalent alternative easements.

This is an exhaustive list. An agency cannot deny a map for reasons outside these statutory findings, and a developer who believes a denial rests on something else has grounds for a legal challenge. General plan inconsistency and environmental damage are the findings cited most often, and the environmental-damage finding frequently overlaps with CEQA.

Conditions of Approval and Improvement Agreements

Most tentative maps receive conditional approval rather than outright approval. Conditions usually require the developer to build or upgrade public infrastructure before recording a final map, including streets, sidewalks, curbs, gutters, storm drains, sewer lines, and water mains sized for the new development.

Conditions have to bear a reasonable relationship to the project’s actual impacts. An agency cannot use tentative map approval as leverage to extract unrelated improvements. If a developer thinks a condition is excessive, the appeal process is the first remedy.

When a developer is ready to record the final map but has not finished the required public improvements, the agency requires an improvement agreement backed by financial security.⁷ The developer either agrees to complete the improvements at its own expense or agrees to finance them through a special assessment district or Mello-Roos community facilities district. Either way the agreement must be guaranteed by security, typically a surety bond, an irrevocable letter of credit, or a cash deposit.

A local agency can disapprove a final map only for failure to meet conditions that were in place at the time the tentative map was approved.⁸ The agency cannot add new requirements between the tentative and final stages. If a final map is disapproved, the agency has to issue a written finding identifying exactly which conditions were not met, and local ordinances must include a waiver procedure for technical or inadvertent errors that don’t materially affect the map’s validity.

How Long an Approval Lasts

An approved or conditionally approved tentative map expires 24 months after approval. A local ordinance can add up to another 24 months, giving a maximum initial life of four years without any extension request.⁹

Beyond the initial period, a developer can apply for discretionary extensions totaling up to six additional years. The legislative body or authorized advisory agency grants these, stacking on top of whatever initial period the local ordinance allows. A developer who receives the full initial period plus the full extension allowance could hold approval for roughly ten years before recording a final map, though that outcome is uncommon.⁹

The extension application must be filed before the map expires. Once filed, the map automatically extends for 60 days or until the agency acts on the request, whichever comes first. If the advisory agency denies the extension, the developer has 15 days to appeal to the legislative body. Missing the deadline is fatal. Once a tentative map expires the developer starts the entire application over, including new environmental review, new fees, and potentially new conditions reflecting zoning or general plan changes adopted in the meantime.

Vesting Tentative Maps

Any time the Map Act requires a tentative map, a vesting tentative map may be filed instead.¹⁰ The difference is legal certainty. When a local agency approves a vesting tentative map, the developer gains a vested right to build under the ordinances, policies, and standards in effect at the time of approval. If the city later downzones the area or adopts stricter setback rules, those changes do not apply to the vested project. That protection matters most on large subdivisions that take years to build out.

The vesting right is not absolute. The agency can still impose conditions or deny a later permit if failing to do so would endanger the health or safety of residents in the subdivision or surrounding community, or if a condition is necessary to comply with state or federal law.¹⁰ Vested rights also lapse if the developer doesn’t obtain final map approval before the tentative map expires, so the same expiration and extension rules apply.

Condominium Conversions

Converting an existing apartment building or rental property into condominiums, a community apartment project, or a stock cooperative triggers the tentative map requirement whenever five or more units are involved.¹ Conversions carry extra tenant-notice obligations on top of the standard process.

Before approving a final map for a conversion, the agency must confirm that every tenant received each of these notices under Section 66427.1:¹¹

Written notice of intent to convert at least 60 days before the tentative map is filed.
Ten days’ written notice that the subdivider has applied or will apply for a public report from the Bureau of Real Estate.
Written notice within five days after the subdivider receives the public report.
Written notice within 10 days after the final map is approved.
At least 180 days’ written notice before the landlord can end a tenancy due to the conversion.
An exclusive right to buy the tenant’s unit on terms at least as favorable as those offered to the public, lasting a minimum of 90 days after the public report issues.

These protections are mandatory and cannot be waived by the local agency. If a rental agreement was negotiated in Spanish, Chinese, Tagalog, Vietnamese, or Korean, the required notices must be provided in that language as well.

1
California Legislative Information. California Government Code 66426 – Tentative and Final Map Requirements
2
California Legislative Information. California Government Code 66424.5 – Tentative Map Definition
3
U.S. Environmental Protection Agency. Permit Program Under CWA Section 404
4
eCFR. Title 50 Section 222.307 – Permits for Incidental Taking of Species
5
California Legislative Information. California Government Code 66452.1 – Action on Tentative Maps
6
California Legislative Information. California Government Code 66474 – Denial of Tentative Maps
7
California Legislative Information. California Government Code 66462 – Subdivision Improvement Agreements
8
California Legislative Information. California Government Code 66473 – Disapproval of Maps
9
California Legislative Information. California Government Code 66452.6 – Tentative Map Expiration
10
California Legislative Information. California Government Code 66498.1 – Vesting Tentative Maps
11
California Legislative Information. California Government Code 66427.1 – Conversion of Residential Real Property