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Sonoma County · Renting & eviction

Rent increases in Sonoma County

Sonoma County's own rules on rent increases, with the code text for every value, and the state law underneath.

Ask about rent increases in Sonoma County See coverage

Each rule below links to the section of the Sonoma County Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What Sonoma County's code says

Sonoma County code What Sonoma County's code adds
Annual increase limit
  • 70% of the CPI percent change or 4%, whichever is less.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; 1 increase in any 12-month period.
    § 2-193 · code text
    Four (4) percent, whichever may be less.
Floor or ceiling on the increase
  • No more than 5% of the current base rent.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; increase when a mobile home is sold in place to a future or current resident.
    § 2-211 · code text
    the parkowner may increase the rent by an amount that does not exceed five percent (5%) of the then current base rent.
Units covered
  • Unincorporated Sonoma County mobile home park spaces, except those under a state-qualifying lease or legally exempt from local rent control.
    § 2-191 · code text
    "Affected residents" means those residents whose space is not covered by a valid lease meeting the requirements as outlined in Section 798.17(b) of the California Civil Code or otherwise legally exempt from local rent control regulation.
  • An RV space occupied by an RV for more than 9 months counts as a mobile home space.
    Applies: RV spaces in mobile home parks in unincorporated Sonoma County; occupancy on or after October 1, 1991.
    § 2-212 · code text
    Any recreational vehicle space that is occupied by a recreational vehicle as defined in Civil Code Section 799.24 for a period in excess of nine (9) months on or after October 1, 1991, shall be regarded to be a "mobilehome space" for purposes of this article
How often rent can go up
  • No more than once in any 12-month period.
    Applies: Mobile home park spaces in unincorporated Sonoma County only.
    § 2-193 · code text
    the space rent payable for use or occupancy of any mobilehome space shall not be increased, in any twelve-month period, more than once.
  • An arbitrator may allow no more than 1 rent increase per park per 12-month period.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; increases in the rent dispute process.
    § 2-195 · code text
    The arbitrator shall not allow more than one (1) rent increase per park per twelve-month period.
Petitions and pass-throughs
  • An arbitrator may consider operating-cost increases, completed capital improvements or substantial rehab, some debt-service increases, and other listed factors.
    Also rental history, park condition, service changes, comparable rents, net operating income, fair return. Owner increases in arbitration; unincorporated Sonoma County mobile home spaces only.
    § 2-199 · code text
    In evaluating the space increase proposed or imposed by the owner, the following factors may be considered:
  • Claims need an amortization table over proven useful life; approved costs appear separately on monthly invoices; rent drops after amortization.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; approved capital improvements primarily benefiting residents of the whole park.
    § 2-191 · code text
    Proposed capital improvements claims must set forth an amortization table spreading the cost of the improvement over its proven useful life. Such costs must be separately itemized, if approved, on the monthly rent invoice.
  • An increase larger than the standard limit must follow the procedures the ordinance sets for it.
    Applies: Increase above 70% of CPI change or 4% in 12 months, other than the administration fee pass-through; unincorporated Sonoma County mobile home spaces only.
    § 2-193 · code text
    In the event an owner wishes to increase the rent payable for any mobilehome space within a twelve-month period more than the amount permitted in subsection (a) of this section for any reason other than that stated in subsection (b) of this section, the procedures set forth in Sections 2-194 and 2-195 shall be followed.
  • Mandatory meet-and-confer and arbitration; owner must show good cause; arbitrator may reduce the increase to a fair return on investment.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; proposed increase above 300% of the CPI percent change within 12 months.
    § 2-193 · code text
    In the event an owner wishes to increase the rent payable for any mobilehome space within a twelve-month period more than three hundred percent (300%) of the percent change in the Consumer Price Index, a mandatory meet-and-confer meeting and arbitration shall automatically be required to show good cause why such an increase is necessary.
  • Capital improvements not otherwise allowed as state-law pass-throughs must be claimed within 12 months of completion, construction, or final billing.
    Applies: Mobile home park spaces in unincorporated Sonoma County only; a rent increase notice that includes a proposed capital improvement.
    § 2-193 · code text
    A notice of rent increase incorporating within it a proposed capital improvement which is not otherwise authorized as a pass-through pursuant to Civil Code Section 798.49 must be claimed within twelve (12) months of the completion of the project, construction or final billing.

Also in Sonoma County's code: Mobilehome Park Space Rent Stabilization (Ch. 2, Art. XIX) — mobilehome park spaces only. This page does not summarize it yet.

The California rule underneath

Where Sonoma County's rule above does not cover a situation, state law still applies. For the statewide rule on its own, see California's statewide rent cap.

CA state law The statewide rule underneath
Rent cap right now
8.6% for increases taking effect August 1, 2026 through July 31, 2027 (5% plus 3.6% inflation)
Applies: Covered units only. Inflation is the California consumer price index (Department of Industrial Relations), used for counties outside the four metro areas, April to April, as the statute requires; the figure is recomputed every year.
Civ. Code § 1947.12(a)(1), (g)
Statewide rent increase cap (AB 1482)
5% plus the change in cost of living, or 10%, whichever is lower, over any 12 months
Applies: Covered units only; measured against the lowest rent charged in the prior 12 months.
Civ. Code § 1947.12(a)(1)
Number of rent increases
No more than two increases in any 12-month period
Civ. Code § 1947.12(a)(2)
Rent cap — new construction exemption
Housing with a certificate of occupancy issued within the previous 15 years is exempt (rolling)
Applies: Mobilehomes excepted.
Civ. Code § 1947.12(d)(4)
Rent cap — single-family home or condo exemption
A home or condo that can be sold on its own is exempt when the owner is not a REIT, a corporation or an LLC with a corporate member, and the tenant was given the written exemption notice
Applies: The same exemption applies to the just-cause rule (§ 1946.2(e)(8)).
Civ. Code § 1947.12(d)(5)
Rent cap — owner-occupied duplex exemption
A duplex in one building is exempt when the owner lived in the other unit at the start of the tenancy and still does, unless either unit is an ADU or JADU
Civ. Code § 1947.12(d)(6)
New tenancy resets the rent
When no prior tenant remains, the owner may set the initial rent; the cap applies to later increases
Civ. Code § 1947.12(b)
Rent cap sunset
§ 1947.12 is repealed on January 1, 2030 unless extended
Civ. Code § 1947.12(o)

Who this affects

TenantsLandlordsProperty managers

Frequently asked questions

How much can rent go up in Sonoma County?

Sonoma County's code: 70% of the CPI percent change or 4%, whichever is less. (Mobile home park spaces in unincorporated Sonoma County only; 1 increase in any 12-month period.) (§ 2-193); No more than 5% of the current base rent. (Mobile home park spaces in unincorporated Sonoma County only; increase when a mobile home is sold in place to a future or current resident.) (§ 2-211). State law: 8.6% for increases taking effect August 1, 2026 through July 31, 2027 (5% plus 3.6% inflation) (Civ. Code § 1947.12(a)(1), (g)).

General information, not legal advice.

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More on renting & eviction in Sonoma County

All renting & eviction rules in Sonoma County

Notices in Sonoma County

California's statewide rent cap

Sonoma County Municipal Code — full text