Unincorporated San Mateo County does not codify a specific numeric annual cap on garage sales per household, but treats sales as permissible incidental residential use when occasional — typically understood as 2-4 per year. Holding sales with greater frequency or for extended durations can trigger home-business zoning review, require a business license, and constitute an unpermitted retail use of residential property. HOA communities often impose stricter limits (commonly 1-2 per year).
While the County has no rigid numeric cap in Title 6 Zoning, enforcement interprets 'occasional' as 2-4 sales per household per calendar year, each lasting 1-3 consecutive days. This interpretation parallels most San Mateo County cities that do specify caps — City of San Mateo's Chapter 5.64 allows 2 sales per year at 2 days each; Redwood City and Belmont have similar limits. Multi-family or neighborhood-wide/HOA-wide community sales are typically treated as a single event for frequency-count purposes. Exceeding the occasional threshold triggers two concerns: (1) zoning interpretation that the property is being used for ongoing retail (a home occupation or unpermitted retail use requiring a business license and zoning clearance), and (2) sales tax obligations once sales become a regular commercial activity (CDTFA seller's permit required at 3+ sales per 12 months under Publication 31). Church, school, nonprofit, and HOA charity sales are generally treated separately with their own rules under the County's occasional-use allowance.
Exceeding occasional-use threshold: zoning violation $100-$500, required business license application. Operating as unlicensed retail: CDTFA back-sales-tax assessment plus penalties. HOA violations: separate HOA fines and legal action by association.
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See how San Mateo County's frequency limits rules stack up against other locations.
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