San Mateo, CA Home Business: Home Occupation Permits (2026)

Unlike many California jurisdictions that issue a 'home occupation permit,' the unincorporated County allows qualifying home occupations without a separate permit. The County Planning and Building Department states that no separate permit is required for a customary, incidental home occupation conducted within a dwelling, provided all conditions are met. Those conditions, drawn from the Zoning Regulations (historically Section 6102.46, now carried into the Title 8 Development Code adopted October 8, 2024), include: the use is conducted within the dwelling in the RE, RH, R-1, R-2, R-3, R-3-A, RM, RM-CZ or PAD districts; no retail business and no stock in trade kept or commodity sold (except items made on-site); no non-resident employees; no more than one-fourth of the ground-floor area used; the entrance to the space is from within the building; no internal or external alterations; no display visible from the street; and only one non-illuminated name plate up to 2 square feet. Because compliance is self-determined, the owner is responsible for meeting every condition; if a business cannot fit within them, it is not a permitted home occupation and would require a different land-use approval or a non-residential location. A County business license and any state requirements (for example, sales-tax registration) may still apply depending on the activity.