San Mateo County · Renting & eviction
Rent increases in San Mateo County
County rule, mobilehome park spaces only: increases are limited to 75% of the CPI change or 5%, whichever is less, once per 12 months. State law caps rent increases on covered units at 8.8% for increases taking effect August 1, 2026 through July 31, 2027.
Key points
- Mobilehome rents: County rule, mobilehome park spaces only: increases are limited to 75% of the CPI change or 5%, whichever is less, once per 12 months.
- Rent cap: State law caps rent increases on covered units at 8.8% for increases taking effect August 1, 2026 through July 31, 2027.
Each rule below links to the section of the San Mateo County Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.
What San Mateo County's code says
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| How often rent can go up |
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| Petitions and pass-throughs |
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Also in San Mateo County's code: Mobilehome Rent Control (Ch. 1.30) — mobilehome park spaces only. This page does not summarize it yet.
The California rule underneath
Where San Mateo 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.
| Rent cap right now | 8.8% for increases taking effect August 1, 2026 through July 31, 2027 (5% plus 3.8% inflation) Applies: Covered units only. Inflation is the BLS consumer price index for the San Francisco-Oakland-Hayward area, April to April, as the statute requires; the figure is recomputed every year. |
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| 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. |
| Number of rent increases | No more than two increases in any 12-month period |
| Rent cap — new construction exemption | Housing with a certificate of occupancy issued within the previous 15 years is exempt (rolling) Applies: Mobilehomes excepted. |
| 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)). |
| 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 |
| New tenancy resets the rent | When no prior tenant remains, the owner may set the initial rent; the cap applies to later increases |
| Rent cap sunset | § 1947.12 is repealed on January 1, 2030 unless extended |
Who this affects
Frequently asked questions
How much can rent go up in San Mateo County?
County rule, mobilehome park spaces only: increases are limited to 75% of the CPI change or 5%, whichever is less, once per 12 months. State law caps rent increases on covered units at 8.8% for increases taking effect August 1, 2026 through July 31, 2027.
General information, not legal advice.
Ask about a specific San Mateo County property
Ask GoCodebook how San Mateo County's rent increases rules apply to your situation and get an answer that cites the section.
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