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

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

Key Facts

Notice method
Certified letter to tenants
Filing deadline
60 days before increase
Applies to
Mobilehome park spaces only
Geographic scope
Unincorporated county only
Standard cap
75% of CPI or 5%

Summary

In unincorporated San Mateo County, a mobilehome park owner seeking a space-rent increase above the standard CPI cap must file a petition with the County Hearing Officer 60 days beforehand and send affected tenants a certified notice letter stating the requested amount.

These county ordinances apply to unincorporated areas of San Mateo County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

The petition shall be filed with the Hearing Officer no later than sixty (60) days before the desired date the requested rent increase is to take effect.3.The petition shall contain a copy of a certified letter sent to the affected tenants notifying them of the petition and the amount of increase requested.4.The petition shall contain a statement attesting to the availability of any records required by the Hearing Officer to complete his or her review of the request for rent adjustment. Records shall include, but not be limited to, any audits of the mobilehome park's books, financial statements, and records relating to any governmental or utility assessments which have been levied upon the mobilehome park.5.The petition shall be accompanied by a check or money order in the amount of two thousand dollars ($2,000.00) to cover costs incurred by the County in fulfilling the Hearing Officer's responsibilities. The fee is nonrefundable. However, at the conclusion of the hearing, and upon making a finding that the petitioner has both successfully pursued the petition and pursued it in good faith, the Hearing Officer may grant to the petitioner a monthly surcharge to be added to the rents of the tenants to recover this fee paid to the County. Such a surcharge shall be a limited-duration pass-through to be paid monthly by the tenants over a period of five years.6.The petition shall be submitted under penalty of perjury. (Ord. 4188, 9/23/03)

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).

Full Breakdown

Chapter 1.30's rent adjustment process (Ord. Code § 1.30.040(B)) governs only mobilehome park spaces in the unincorporated county, and only increases above the annual cap set by § 1.30.030 (75% of the CPI change or 5%, whichever is less). To seek a larger increase, the park owner must file a petition with the Hearing Officer no later than 60 days before the desired effective date, accompanied by a certified letter sent to the affected tenants notifying them of the petition and the exact amount of increase requested. Standard CPI-capped increases carry no separate notice mandate in this chapter.

Violations & Fines

Under § 1.30.090, a tenant may refuse to pay any rent increase issued in violation of this chapter; that refusal is a valid legal defense against any action brought to recover possession of the mobilehome space or to collect the increase.

Frequently Asked Questions

Does this notice rule cover apartment rent increases?
No. Chapter 1.30 covers only mobilehome park spaces in the unincorporated county; apartment and house rentals fall under state law, Civil Code § 1947.12.
What if a park owner raises rent above the cap without notice?
Under § 1.30.090 the tenant may refuse to pay the unauthorized increase, and that refusal is a defense in any eviction or collection action.

Sources & Official References

Other rules in San Mateo County

All San Mateo County rules

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