Unincorporated San Mateo County does not require a permit for occasional residential garage/yard sales. Sales are treated as incidental residential activity, not commercial operations, so long as they remain occasional and comply with County Code frequency and sign rules. Merchandise must be personal property, not goods purchased for resale — the latter would require a business license and zoning clearance as a home business or retail operation.
Occasional garage and yard sales in unincorporated San Mateo County are permitted without a permit under the general zoning framework that treats them as incidental to residential use. The County does not operate a permit/registration system like some neighboring cities (City of San Mateo's Chapter 5.64 requires registration there). However, sales must remain occasional — generally not more than 2-4 per year per household — and cannot become a pattern of recurring retail activity, which would trigger home-business zoning compliance or require a business license and county health/regulatory approval depending on goods sold. Merchandise must be the household's own used personal property; reselling new or commercially purchased goods crosses into retail and triggers state sales tax (CDTFA) registration. HOA communities often have separate garage sale rules including limited permitted days and mandatory HOA notification; these private rules run alongside (not in place of) County regulation.
Operating as ongoing retail business without license: $100-$500 per County Code, plus CDTFA back-tax assessment for unreported sales. Sign violations: $25-$50 per sign. Obstructing public right-of-way with merchandise/parking: removal and $100-$250 citation.
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See how San Mateo County's garage sale permits rules stack up against other locations.
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