The Foster City sales tax rate is 9.375% in 2026. That total combines California’s 7.25% statewide base with 2.125% in voter-approved district taxes that apply across San Mateo County.1California Department of Tax and Fee Administration. California City and County Sales and Use Tax Rates It sits on the lower end for the county, which can matter when you’re pricing out a large purchase.
What Makes Up the 9.375%
The 7.25% statewide base is actually six separate levies bundled together. Most of that money flows to state funds, with only 1.25% going directly to local government by default: 0.25% for county transportation and 1.00% for city or county operations.2California Department of Tax and Fee Administration. Detailed Description of the Sales and Use Tax Rate
The remaining 2.125% comes from district taxes San Mateo County voters have approved over the years. Two countywide half-cent measures do most of the work. Measure K, approved in 2016 as a 20-year extension of an earlier measure, funds general county needs through 2043.3San Mateo County Measure K. About Measure K Measure W took effect in July 2019 and runs through 2049; half of its revenue supports SamTrans bus service and Caltrain, and the rest goes to highway projects, local roads, bicycle and pedestrian infrastructure, and regional transit.4San Mateo County Transportation Authority. Measure W The San Mateo County Transit District levies an additional portion on top.
How Foster City Compares to Neighboring Cities
Foster City’s rate is lower than most of its neighbors. The city of San Mateo charges 9.625%, while Redwood City and Belmont both sit at 9.875%.1California Department of Tax and Fee Administration. California City and County Sales and Use Tax Rates Those higher rates reflect additional city-level measures Foster City hasn’t adopted. On a $1,000 purchase, the gap between Foster City and Redwood City is $5. On furniture, appliances, or electronics, the arithmetic adds up.
What’s Taxable and What’s Exempt
California sales tax applies to tangible personal property, meaning physical items you can see, touch, or weigh.5California Department of Tax and Fee Administration. Revenue and Taxation Code 6016 – Tangible Personal Property Electronics, clothing, furniture, vehicles, and building materials all ring up at the full 9.375% in Foster City. Several important categories are carved out.
Groceries
Most food bought for home consumption is exempt. That covers produce, meat, dairy, eggs, bread, cereal, canned goods, frozen meals, bottled water, and fruit juices.6California Legislative Information. California Revenue and Taxation Code 6359 Carbonated beverages and alcohol don’t qualify, so sparkling water and beer are taxed. Candy and gum fall under the food products definition and stay exempt when sold at a grocery store for take-home consumption.
Prepared Food and Restaurant Meals
The grocery exemption disappears once food is prepared for immediate consumption. Hot food is always taxable, wherever you buy it. A rotisserie chicken from the grocery store deli is taxable; a raw chicken from the meat case is not. Restaurant meals are taxable whether you dine in or take them out. Drive-through orders are taxable. Food sold at venues that charge admission is taxable.
There’s also an “80-80 rule” worth knowing. If more than 80% of a seller’s revenue comes from food products, and more than 80% of those food sales are already taxable, then even their cold prepared foods sold to go become taxable. That’s why a sandwich from a restaurant is taxed even if you take it home, while the same sandwich from a grocery store deli counter might not be, depending on the store’s sales mix.
Prescription Medicines
Medicines prescribed by a doctor, dentist, or podiatrist and filled by a pharmacist are fully exempt.7California Department of Tax and Fee Administration. Revenue and Taxation Code 6369 – Prescription Medicines Over-the-counter drugs are taxable. Medical devices like bandages, splints, and prosthetics are also taxable, since the exemption covers medicines specifically rather than medical supplies broadly.
Services
Professional services like legal advice, accounting, consulting, and haircuts generally aren’t subject to sales tax. The line gets blurry when a service produces a physical product. A graphic designer who emails you a digital file typically doesn’t charge sales tax, but one who delivers printed marketing materials may need to collect tax on the tangible portion.
Online Purchases and Use Tax
Online purchases shipped to Foster City are generally taxed at 9.375%. Since 2019, any out-of-state seller with more than $500,000 in annual California sales must register with the state and collect sales tax, including applicable district taxes, based on the delivery address.8California Department of Tax and Fee Administration. Tax Rate FAQ for Sales and Use Tax For packages headed to Foster City, that means the full local rate shows up at checkout for virtually every major retailer.
California is primarily an origin-based state for its base sales tax, meaning tax on in-state sales is typically allocated to where the seller operates. For the district taxes that make up Foster City’s extra 2.125%, the rules flip to destination-based sourcing: if a seller is engaged in business in the district where goods are shipped, they collect that district’s tax from the buyer.
When an out-of-state seller doesn’t collect tax, the obligation doesn’t vanish. You owe what California calls “use tax” on those purchases. The easiest way to pay it is on your California state income tax return, which includes a line item and worksheet for the calculation. You can also pay directly through the CDTFA’s online portal.9California Department of Tax and Fee Administration. California Use Tax, Good for You. Good for California Most people owe very little in use tax now that the $500,000 economic nexus threshold captures the large online retailers, but it still applies to purchases from small out-of-state sellers, private party sales, and items bought while traveling.
If You Sell in Foster City
Any business that sells or leases tangible personal property in California needs a seller’s permit from the CDTFA before making its first sale. That applies to brick-and-mortar shops, farmers market vendors, and online stores that ship from a California warehouse. Out-of-state businesses also need a permit if they have a physical presence in the state or exceed $500,000 in California sales.10California Department of Tax and Fee Administration. Your California Sellers Permit The permit itself is free through the CDTFA’s online registration system, though the agency may require a security deposit to cover potential future tax liability.11California Department of Tax and Fee Administration. Obtaining a Sellers Permit If you’re only selling at a temporary event lasting 30 days or less at a single location, you’ll apply for a temporary seller’s permit instead.
Once registered, the CDTFA assigns a filing frequency based on your sales volume: monthly, quarterly with prepayments, quarterly, or annually.12California Department of Tax and Fee Administration. Filing Dates for Sales and Use Tax Returns Missing a deadline triggers a 10% penalty on the unpaid tax, plus monthly interest at the federal IRS underpayment rate plus three percentage points.13California Department of Tax and Fee Administration. Interest, Penalties, and Collection Cost Recovery Fee