Definition
Annexation is the legal process by which a city (or other local agency) incorporates adjacent unincorporated territory within its jurisdictional boundaries. Once annexed, the territory becomes part of the city, subject to city land use regulations, taxes, and service responsibilities. Residents and businesses in the annexed area typically gain access to city services — water, sewer, police, fire — and become subject to city taxes and fees.
LAFCO's Role
All annexations in California must be reviewed and approved by the Local Agency Formation Commission (LAFCO) of the county in which the territory is located. LAFCO evaluates whether an annexation is consistent with the city's adopted sphere of influence — the LAFCO-approved planning boundary within which the city is expected to grow over time. Annexations outside the sphere of influence require LAFCO to first amend the sphere, which is a separate, more complex process.
LAFCO considers factors including:
- Consistency with the sphere of influence
- Adequacy of city services to be extended
- Effects on agricultural land and open space
- Fiscal impacts on the annexing city and the county
- Effects on existing special districts serving the area
Voter Protest and Election Requirements
After LAFCO approves an annexation, a protest period opens. If a sufficient number of registered voters or landowners protest, the annexation may be submitted to a vote. If a majority of registered voters in the affected area vote against annexation, it fails. Uncontested annexations with little or no protest can proceed without an election.
Pre-Zoning
Before annexing territory, cities often pre-zone it — applying city zoning designations to the unincorporated territory in advance of annexation. Pre-zoning is a standard practice that allows future residents and landowners to know what development will be permitted after annexation occurs.
Annexation is a multi-agency, multi-step process with significant land use, fiscal, and political dimensions. Legislaide helps cities navigate LAFCO processes, structure pre-annexation service agreements, and manage the land use transitions that accompany annexation.
Frequently Asked Questions
What does annexation mean?
Annexation is the legal process by which a city extends its boundaries to absorb adjacent unincorporated land. Once annexed, that territory becomes part of the city and is subject to city zoning, taxes, and services such as water, sewer, police, and fire.
Who approves an annexation?
In California, every annexation must be reviewed and approved by the county's Local Agency Formation Commission (LAFCO). LAFCO checks that the annexation fits the city's adopted sphere of influence and that the city can adequately serve the new territory. Other states use comparable boundary-review bodies or council-led processes.
Can residents stop an annexation?
Yes. After LAFCO approves an annexation, a protest period opens. If enough registered voters or landowners in the affected area protest, the annexation goes to a vote — and if a majority votes against it, the annexation fails. Uncontested annexations can proceed without an election.
What is a sphere of influence?
A sphere of influence is the LAFCO-approved planning boundary that defines the area a city is expected to grow into over time. Annexations inside the sphere are straightforward; annexing land outside it first requires LAFCO to amend the sphere, a separate and more complex step.
What is pre-zoning in an annexation?
Pre-zoning is when a city applies its zoning designations to unincorporated land before annexing it. It is standard practice that tells future residents and landowners exactly what development will be permitted once the territory becomes part of the city.
Published June 15, 2026 by Legal Team at Legislaide. Last updated June 17, 2026.