San Mateo, California Short-Term Rental Regulations: A 2026 Guide For Airbnb Hosts

Do you own a place in San Mateo County, California and you're weighing whether to put it on Airbnb or Vrbo? Well, the good news is that the county does allow short-term rentals, but there's a big catch, and it comes down almost entirely to where your property sits. San Mateo County only permits them in the unincorporated Coastal Zone, the Midcoast stretch around Montara, Moss Beach, El Granada and Princeton, and even there you need a permit first. Own a place in one of the bayside unincorporated pockets instead, and unfortunately there's no county permit to apply for at all, which effectively means you can't run a legal nightly rental on it.

So the very first thing to sort out isn't the paperwork, it's your address. Once you've confirmed the parcel is inside the Coastal Zone and zoned for single-family or multi-family use, the rest follows a fairly standard shape: a permit from the Planning and Building Department, a 180-night annual cap, a 10% transient occupancy tax you collect and remit yourself, and a short list of safety and neighbor rules baked into the permit. Keep in mind too that this guide is about unincorporated county land only. Incorporated cities like the City of San Mateo, Half Moon Bay and Daly City each run their own registration schemes, so if your property sits inside city limits, those local rules govern instead.

What follows walks through all of it for 2026: whether you can operate where you are, what the permit takes and costs, the taxes stacked on a stay, how hard the county pushes on enforcement, and who to call when something snags. Every figure here comes from San Mateo County's or California's own pages, checked in July 2026, and where a number tends to move I've said so. Before you spend a dollar chasing a permit, it's worth running the property through BNBCalc first to see whether 180 capped nights on the coast actually pencil out.

Starting a Short-Term Rental Business in San Mateo County

Since your address decides everything, that's where any honest plan has to start. San Mateo County's short-term rental rules live in Ordinance 4777, adopted by the Board of Supervisors in June 2017, and the ordinance did something narrow on purpose. It amended the zoning code to add short-term rentals as an allowed use "In the Coastal Zone" only, on parcels zoned Single Family (R-1) or Multi-Family (R-3). Everywhere else in the unincorporated county, the code simply never made a nightly rental a permitted use, so there's no application to file and no path to legality.

That coastal-only design is the piece most new hosts miss, and it matters because "unincorporated San Mateo County" sounds like one place when it's really two. The Coastal Zone covers the Midcoast communities on the ocean side of the hills, and that's the only part of the county where the Planning and Building Department will issue a permit. The bayside unincorporated areas, places like North Fair Oaks or the pockets around Redwood City, sit outside the ordinance entirely. Assuming your parcel falls there, the realistic move is a stay of 30 days or longer, which isn't a short-term rental under the law and drops you into ordinary landlord and tenant territory instead.

There's a second reason the coast is treated carefully, and it reaches above the county. Because these parcels sit in the Coastal Zone, the ordinance had to run through the county's Local Coastal Program and take effect only once the California Coastal Commission certified it. Your individual permit inherits that layer, so a coastal short-term rental has to conform to the Local Coastal Program and honor any Coastal Development Permit conditions attached to the property. It's not a hurdle you'll usually feel day to day, but do be aware it's the reason the county can't simply loosen the rules on its own.

One more thing worth settling before you get attached to a plan. The ordinance excludes accessory dwelling units and second units from short-term rental use, so you can't build a granny flat and put it on Airbnb by the night. That lines up with California's statewide rule, Government Code § 66323, which requires ADU rentals to run longer than 30 days. So the thing you're permitting is the main home, or a room within it, on a qualifying coastal parcel, and nothing else.

Short-Term Rental Licensing Requirement in San Mateo County

Once you've confirmed your parcel is coastal and correctly zoned, the permit itself is still the gate you have to clear, and it's a real one rather than a rubber stamp. Every short-term rental needs a valid Short-Term Rental Permit from the Planning and Building Department, one per property address, applied for through the county's Accela Citizen Access portal. As of July 2026, the approximate fee is $500 and processing runs about three to four weeks, and the department encourages you to book a call with a planner before you file so you don't burn that fee on an application that was never going to clear.

Only an owner can apply, meaning someone who holds fee title or a lease of at least 30 days, and a tenant applying has to include written authorization from the property owner. The permit expires automatically three years after issuance, or the moment you no longer own or lease the place, whichever comes first. You can renew up to six months before it lapses, using the same application process as the first time around, so don't forget to diarize that date because letting it expire means starting over.

The single number that shapes the whole business model is the nightly cap. A San Mateo County short-term rental can't be rented for more than 180 nights per calendar year, which is half the year gone before you begin. There's one genuinely useful wrinkle, though: any night you're physically present at the property while it's rented doesn't count against the 180. So an owner who lives on-site and hosts a room can run far more nights than an absentee owner renting the whole house, and that difference is worth modeling carefully before you buy.

Beyond the cap, the ordinance folds a set of performance standards straight into the permit, and you're agreeing to all of them when you accept it. The ones that most affect how you run the place:

• Occupancy is capped by bedrooms. You can host up to two people per bedroom rented plus two more, so a one-bedroom rental tops out at four guests. Children under 12 don't count toward the limit.
• On-site parking is mandatory. You need at least one on-site space in a garage, driveway or lot, and at least two if occupancy tops eight tenants.
• A local contact person has to be reachable at all times. They must stay within a 20-mile radius and be able to physically show up within an hour in an emergency. You can be your own contact if you qualify, and the county shares that name and number with the Sheriff, the local fire agency and every neighbor within 100 feet.
• Safety equipment is checked before issuance. Smoke alarms in and outside each bedroom and on every level, carbon monoxide alarms outside each bedroom and on every level, and at least one fire extinguisher per habitable floor.
• You carry real insurance. The owner must keep at least $500,000 in liability coverage while the place is occupied.
• No exterior signage. Nothing advertising the rental can be visible from outside, windows included.

Watch out for the advertising rule while your application is pending, too. It's unlawful to advertise a short-term rental without a valid permit, and each day you do counts as a separate violation, so hold off on the listing until the permit is actually in hand.

Required Documents for San Mateo County Short-Term Rentals

Because that $500 fee doesn't come back if your file is incomplete, it pays to assemble the whole packet before you open the portal. The application the Planning and Building Department requires is specific about what goes in it, and a missing piece is the usual reason a submission stalls. Here's what you'll be uploading:

• The completed application form, signed by the owner certifying the information is true.
• A copy of your rental or lease agreement or the advertisement itself, and it has to recite the performance standards: the number of tenants allowed, on-site parking, trash, the ban on illegal activity, and noise.
• A valid Transient Occupancy Registration Certificate from the County of San Mateo under Ordinance Code Chapter 5.136, or other evidence you're compliant with it. This is the tax registration, and you'll want it lined up before you apply rather than after.
• Evidence of on-site parking that meets the space requirement.
• Proof the property's street number is visible from the road, so emergency services can find it.
• Proof of at least $500,000 in liability insurance on the rental.

Keep in mind the county won't approve a permit if you've got outstanding compliance problems, so any open liens, fines, unpaid tax or code violations need clearing first. If you've had past run-ins with the Tax Collector or Code Compliance, do check those are resolved before you file, because the Community Development Director is directed to deny the application otherwise.

There's also a recordkeeping duty that starts once you're operating. You have to keep accurate records of nights rented and amounts paid, produce them within 10 days if the county asks, and retain them for at least three years. It's dull, but it's exactly the trail the Tax Collector uses in an audit, so make sure you keep it from night one rather than reconstructing it later.

San Mateo County Short-Term Rental Taxes

Assuming you clear the permit and are able to start hosting, there's still tax to deal with, and the county's piece is the one you administer yourself. San Mateo County charges a transient occupancy tax (TOT) of 10% of the rent on any stay under 30 days, authorized under Ordinance Code Chapter 5.136 and California's Revenue and Taxation Code § 7280, which lets any county tax short stays. "Rent" is broader than the nightly rate too, so it sweeps in cleaning fees, roll-away bed charges and package lodging value. A guest who stays 30 days or more isn't a transient and owes no TOT.

Here's the part that catches Bay Area hosts used to other markets: for unincorporated San Mateo County, Airbnb does not collect this tax for you. The county contracted with HdL to run TOT collection in October 2022, and the county isn't on Airbnb's list of California jurisdictions where it collects and remits on the host's behalf. So the responsibility to register, collect the 10% and file returns lands on you. You register with the Tax Collector within 30 days of starting, post the certificate you get back, then file quarterly, even in a quarter where you owe nothing.

Charge	Rate	Who collects it
County transient occupancy tax	10% of rent	You remit to the San Mateo County Tax Collector (via HdL)
California income tax on rental profit	Marginal rate	You, via the Franchise Tax Board
California Tourism Assessment	About $1,950 per $1M of lodging revenue	You self-report to the state

Those quarterly returns run on a fixed calendar. Returns cover the quarters ending March, June, September and December, and they're due the last day of the following month: April 30, July 31, October 31 and January 31. Miss a due date and penalties apply the very next day, and the county's own guidance warns that a chronically late operator gets moved to monthly filing and flagged for an immediate audit. So treat the dates as hard.

The other two rows are state-level and easy to overlook. Rental profit is ordinary income to the Franchise Tax Board, residents on everything and nonresidents on California-sourced income. And California runs a statewide Tourism Assessment on lodging revenue, which the Office of Tourism has put at roughly $1,950 per $1 million of accommodations revenue. That rate comes from an older filing, so I'd verify the current figure with the state before you calculate it, but be aware neither of these gets collected by a platform. They're on you.

California Wide Short-Term Rental Rules

Those state assessments are a hint of a broader point, which is that a fair amount of what governs your coastal rental isn't county law at all. California mostly leaves short-term rental rules to cities and counties, so there's no statewide permit, no state registry and no state occupancy tax. Our California short-term rental guide maps the whole framework, but a few state rules reach directly into a San Mateo County coastal listing.

The Coastal Act is the big one here, and it's why your county permit exists in the form it does. The Coastal Commission's 2016 guidance treats short-term rental regulation as "development" that has to run through a Local Coastal Program, and it has historically opposed outright coastal rental bans. That's the backdrop against which San Mateo County chose to permit rentals on the coast rather than prohibit them, which is genuinely good news if you own a qualifying Midcoast parcel.

A few other state layers to keep on your radar:

• Fines are capped by statute. Under Government Code § 25132, a county's penalties for an ordinance violation top out at $1,500 for a first offense, $3,000 for a second within a year and $5,000 after that, with the higher tiers reserved for health-or-safety threats.
• HOA and lease bans still bind you. A county permit doesn't override a homeowners association or lease that prohibits short-term rentals, and Civil Code § 4741 expressly lets an HOA ban stays of 30 days or less. So read your governing documents before anything else.
• Platform data reporting arrived in 2026. The Short-Term Rental Facilitator Act (SB 346), effective January 1, 2026, requires platforms to report each listing's address and carry local permit and TOT details where a local agency has an ordinance in place. It doesn't make the platform collect your TOT, though, which is why the county tax stays your job.

The upshot is that state law here mostly enables the county rather than overriding it, unlike, say, San Francisco's much heavier hand next door. If you're comparing markets, the San Francisco County guide shows how differently the city treats hosts, and the Sonoma County guide covers another California coastal-and-wine market with its own caps.

Does San Mateo County Strictly Enforce STR Rules?

Given how tightly the ordinance is drawn, the fair question is whether the county actually acts on it, and the honest answer is yes, mostly through complaints and the permit itself. Enforcement here isn't the payment-blocking machine you'd find in a big city, but the county built real teeth into Ordinance 4777, and the coast is a small enough community that neighbors notice and report.

The permit is the main lever, because so much can cost you it. More than two documented violations in any 12-month period let the department suspend or revoke your permit, and those violations cover more than noise or parking citations, since failing to produce your rental or tax records on request counts too. Once a permit is revoked, you can't reapply for that same property for at least a year, and you get a hearing before it happens, with an appeal to the Planning Commission.

Operating with no permit at all is treated more harshly still. On top of the monetary penalties under the county's administrative remedies, an unpermitted operator faces a black-out period equal to double the number of days they ran or advertised without a permit. That's a minimum of one month and a maximum of a year during which they can't apply or renew. You also have to pay every dollar of back TOT before the county will even look at an application. Add the state fine caps on top, and casual non-compliance stops being cheap fast.

The neighbor-notification design is what makes it stick. When you're permitted, your local contact's name and number go to the Sheriff, the fire agency and everyone within 100 feet, and complaints route straight back to code compliance. On the tax side, the Tax Collector can record a lien and even seize property for unpaid TOT, and failing to register or filing a false return is a misdemeanor. So while nobody's blocking your bookings at checkout, the county has plenty of ways to make an out-of-line rental unprofitable.

How to Start a Short-Term Rental Business in San Mateo County

So let's walk through the order that actually saves you time and money, because a couple of these steps can end the project before you've spent much on it. Working through them out of sequence is how people lose the application fee or, worse, buy a property they can never legally rent by the night.

1. Confirm the parcel is in the Coastal Zone and zoned R-1 or R-3. This is the go/no-go step. If the property is bayside or the wrong zoning, there's no permit to be had, and a 30-plus-day rental is your realistic option instead.
2. Read your HOA rules and any lease. A county permit won't override a private ban, and plenty of coastside associations restrict short-term rentals. Sort this before you spend anything.
3. Register for transient occupancy tax. Apply to the San Mateo County Tax Collector within 30 days of starting and get your TOT Registration Certificate, since you'll need it inside the permit application anyway.
4. Get the home to safety spec. Install the smoke and carbon monoxide alarms in every required spot and a fire extinguisher on each level, and line up your $500,000 liability policy.
5. Line up your local contact and parking. Name someone within 20 miles who can respond within the hour, and confirm you have the one or two on-site spaces the ordinance requires.
6. Apply and pay the roughly $500 fee through the Accela Citizen Access portal, and expect about three to four weeks plus a 10-day neighbor and Coastal Commission notice window.
7. Post everything the permit requires inside the unit, from the performance standards to the noise ordinance and your contact details, and only then publish the listing.
8. Track your nights and file TOT quarterly. Watch the 180-night cap, remember on-site nights don't count, and keep those records for three years.

Who to Contact in San Mateo County about Short-Term Rental Regulations and Zoning?

Whichever of those steps trips you up, knowing which office owns the question will save you a lot of time on hold. Two county bodies handle nearly everything: the Planning and Building Department for the permit and zoning, and the Tax Collector, through its contractor HdL, for the tax.

The permit, zoning and code compliance

The San Mateo County Planning and Building Department issues the short-term rental permit, confirms whether your parcel qualifies, and handles complaints through code compliance.

• Address: 455 County Center, 2nd Floor, Redwood City, CA 94063
• Planning: (650) 363-1825, or general information at (650) 363-1827
• Code Compliance: (650) 363-4825, [email protected]
• Email: [email protected]
• Hours: Monday to Thursday, 8:00 a.m. to 4:00 p.m., closed noon to 1:00 p.m.
• Apply: the Accela Citizen Access portal

Before you file, do book the pre-application planner appointment the department offers. A ten-minute conversation about your specific parcel is the cheapest way to find out whether the permit is even available to you.

Transient occupancy tax registration and filing

HdL runs TOT registration and quarterly filing for the county, so this is who you deal with for the tax rather than the Planning Department.

• Phone: (415) 869-6687, Monday to Friday, 8:00 a.m. to 5:00 p.m. Pacific
• Email: [email protected]
• Register and file: the San Mateo County TOT portal
• Tax Collector forms and general line: tax.smcgov.org, or (866) 220-0308

If your property turns out to sit inside an incorporated city rather than unincorporated county land, none of the above applies and you'll want that city's own clerk or finance department, since cities like the City of San Mateo run entirely separate registration and tax systems.

What Do Airbnb Hosts in San Mateo County on Reddit and BiggerPockets Think about Local Regulations?

Contacts in hand, it helps to know what operators who've actually gone through this say about it, though what follows is my read of the recurring themes rather than any kind of formal survey, so do weigh it accordingly. Public discussion among Bay Area coastal hosts tends to circle the same few points.

• The address lottery frustrates people most. The recurring surprise is discovering that "unincorporated San Mateo County" doesn't mean a free-for-all, and that a bayside parcel simply can't be permitted. Hosts who assumed the county was uniformly open often find out only after buying.
• The 180-night cap reshapes the math. Experienced operators point out that half a year of legal nights, plus a coast with real seasonality, makes this a supplemental-income market more than an investor-scale one, unless you live on-site and use the owner-present exemption to stretch past the cap.
• The local-contact and neighbor-notification rules draw mixed reactions. Some hosts find the 20-mile, one-hour response rule easy when they live nearby and genuinely annoying when they don't. The notification to neighbors within 100 feet gets described both as fair warning and as an invitation to complaints.
• Nobody argues the county ignores the rules. The consensus is that the coast is small, neighbors are watchful, and the permit is worth protecting, so the debate is about whether the caps are fair rather than whether they're enforced.

Take that last point seriously if you're modeling a coastal purchase, because the realistic path here is a well-run, fully permitted, capped operation rather than a high-volume one, and the numbers have to work inside those limits. To see how the broader state market compares before you commit, the California short-term rental market data is the place to check current benchmarks, and then it's worth deciding whether a permitted 180 nights on the Midcoast beats a whole different market entirely. The rules reward the owner who plans around them rather than fighting them, and on this coast that mindset is really the whole game.

Frequently Asked Questions

Can you legally run an Airbnb in San Mateo County in 2026?

Only in part of it. Unincorporated San Mateo County allows short-term rentals just in its Coastal Zone, the Midcoast communities like Montara, Moss Beach and El Granada, and only on R-1 or R-3 zoned homes with a Short-Term Rental Permit. Bayside unincorporated areas have no permit pathway, so nightly rentals aren't an allowed use there. Incorporated cities within the county set their own separate rules.

How much does a San Mateo County short-term rental permit cost and how long does it last?

The permit fee is approximately $500, and processing takes about three to four weeks through the county's Accela Citizen Access portal. A permit lasts three years from issuance, or until you no longer own or lease the property, whichever comes first. You can renew up to six months before it expires using the same application process. Budget for the $500,000 liability insurance and safety equipment the permit also requires.

What is the transient occupancy tax on a San Mateo County short-term rental?

Unincorporated San Mateo County charges a 10% transient occupancy tax on the rent for any stay under 30 days, including cleaning fees and similar charges. Airbnb does not collect it for the county, so you register with the Tax Collector through HdL, collect the 10% yourself, and file quarterly returns due April 30, July 31, October 31 and January 31. Stays of 30 days or more are exempt.

How many nights a year can you rent a short-term rental in San Mateo County?

A San Mateo County short-term rental is capped at 180 rented nights per calendar year. There's an important exception, though: any night you're physically present at the property while it's rented doesn't count against the cap. So an owner who lives on-site and rents a room can operate well beyond 180 nights, while an absentee owner renting the whole home is held to the limit.

Can you run an Airbnb in the non-coastal parts of unincorporated San Mateo County?

No. Ordinance 4777 added short-term rentals as an allowed use only in the Coastal Zone, so the bayside unincorporated areas have no permit process and nightly rentals aren't permitted there. Your realistic option on a non-coastal parcel is a rental of 30 consecutive days or longer, which falls under ordinary landlord and tenant law rather than the short-term rental ordinance.

Last verified: July 2026. Every ordinance, tax rate, state law, and contact detail in this guide links to or comes from its official source.