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San Mateo County, CA Rental Property Rules: Rent Control (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Rent control rules in San Mateo County, CA, also known as rent stabilization or rent cap ordinances, limit annual rent increases and protect tenants from displacement.

Key Facts

Local Control
None in unincorporated
State Cap
5% + CPI, max 10%
State Law
Civil Code §1947.12
New Build Exempt
Under 15 years
SFR Exempt
If not corp-owned

Summary

Unincorporated San Mateo County has NO local rent control. State law AB 1482 (Tenant Protection Act, Civil Code §1946.2 and §1947.12) caps annual rent increases at 5% plus CPI (maximum 10%) for qualifying units. Single-family homes owned by non-corporate owners and buildings under 15 years old are exempt.

City-specific rules exist: San Mateo has its own rent control rules that differ from San Mateo County's county-level regulations. If you live in San Mateo, check the city-specific page instead.

1947.12.

(a) (1) Subject to subdivision (b), an owner of residential real property shall not, over the course of any 12-month period, increase the gross rental rate for a dwelling or a unit more than 5 percent plus the percentage change in the cost of living, or 10 percent, whichever is lower, of the lowest gross rental rate charged for that dwelling or unit at any time during the 12 months prior to the effective date of the increase. In determining the lowest gross rental amount pursuant to this section, any rent discounts, incentives, concessions, or credits offered by the owner of such unit of residential real property and accepted by the tenant shall be excluded. The gross per-month rental rate and any owner-offered discounts, incentives, concessions, or credits shall be separately listed and identified in the lease or rental agreement or any amendments to an existing lease or rental agreement.

(2) If the same tenant remains in occupancy of a unit of residential real property over any 12-month period, the gross rental rate for the unit of residential real property shall not be increased in more than two increments over that 12-month period, subject to the other restrictions of this subdivision governing gross rental rate increase.

(b) For a new tenancy in which no tenant from the prior tenancy remains in lawful possession of the residential real property, the owner may establish the initial rental rate not subject to subdivision (a). Subdivision (a) is only applicable to subsequent increases after that initial rental rate has been established.

Source: California Legislative InformationView official code

Full Breakdown

San Mateo County has not adopted a local rent stabilization ordinance. Tenants in unincorporated areas (North Fair Oaks, Emerald Hills, West Menlo Park, Montara, Moss Beach, Princeton, El Granada, Loma Mar, La Honda, Pescadero) rely on California Civil Code §1947.12 (AB 1482) which limits annual rent increases to the lesser of 5% plus regional CPI or 10% total. San Francisco-Oakland-Hayward CPI applies. Exemptions include: new construction less than 15 years old (rolling), single-family homes and condos not owned by corporations/REITs/LLCs with corporate members (owner must provide written notice of exemption), deed-restricted affordable housing, and owner-occupied duplexes. Landlords may pass through capital improvement costs subject to state limits. Local cities East Palo Alto and Redwood City have their own rent control; county unincorporated areas do not.

Violations & Fines

Overcharges: tenant entitled to refund of excess rent plus interest. Willful violations: actual damages plus treble damages or $100 minimum, whichever greater, under Civil Code §1947.12(h). Attorneys' fees recoverable. Tenants may file civil action in SMC Superior Court.

Frequently Asked Questions

What are typical penalties for violating rent control rules?
Most San Mateo County rental property violations start with a written warning followed by escalating civil fines for repeat offenses. Specific dollar amounts and any criminal-misdemeanor exposure depend on the section of code; consult San Mateo County's municipal code or staff for the current penalty schedule.

Sources & Official References

Other rules in San Mateo County

All San Mateo County rules

California rules heatmap·Compare San Mateo County to another location·View the California rental property rules overview

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Rent Control in Cities Across San Mateo County