Multifamily and Duplex Properties for Sale in Inverness: Zoning and Rent Rules

What multifamily in Inverness looks like

Inverness has almost no apartment buildings. Its rental housing is mostly single-family homes and cottages, homes with a second unit or ADU, a few older duplexes and cabin clusters, and upstairs or rear units at village commercial buildings. Many homes are second homes, and a large share of rentals have historically been short-term. For an investor, "multifamily" here usually means a house plus a permitted ADU, or a rare legal duplex near the village. For financing, see financing 2-4 unit properties and apartment building loans.

Where the zoning allows it

Inverness is in the Coastal Zone, so Marin County’s coastal districts in Chapter 20.62 apply.

The coastal chapter says zoning densities are maximums, not entitlements, and may not be reached where other LCP policies apply. Every new unit generally needs a Coastal Development Permit. Even a small 2026 addition at 195 Park Avenue needed one, because the house predated 1930 and its septic system was being enlarged.

No Housing Element sites. The county’s West Marin housing sites list includes none in Inverness, so new multifamily supply is unlikely.

ADUs and SB 9. ADUs are allowed in coastal residential districts with a coastal permit unless exempt. See our ADU investment guide. SB 9 excludes coastal zone parcels in many cases and applies only in urbanized areas, so assume it does not apply in Inverness unless the county confirms otherwise; see our SB 9 lot split guide.

Rent rules: state law plus county ordinances

Rent cap. No local cap applies. The Attorney General’s rent cap page sets the AB 1482 cap for the San Francisco area, including Marin, at 8.8% for increases from August 1, 2026 through July 31, 2027. Many Inverness rentals are single-family homes that may be exempt; see our AB 1482 guide.

County just cause. Chapter 5.100, Ordinance 3705 of December 2018, covers properties with three or more units on one legal lot in unincorporated Marin. Short-term rental units count toward the three, as do unpermitted units; permitted ADUs and JADUs do not. A cabin cluster rented partly short-term and partly long-term can fall under it. Valid terminations need a business license, registry entry, tenant rights notice and a copy to the CDA within 10 days. See our just cause eviction guide.

Mediation. Increases above 5% in 12 months go to the county’s mandatory mediation program if the tenant asks within 10 calendar days.

Inverness rental property rules

• Short-term rentals. Inverness is its own STR township. The county’s administrative procedures list 93 initial licenses, falling to 86 through attrition. After the initial two-year term, an owner who ran more than one STR can renew only one. ADUs created after January 1, 2020 under the statewide exemption cannot be licensed. A buyer cannot assume a seller’s STR income will continue.
• Business license and registry. Every rental needs a county business license, $15 per unit per year, and covered units must be in the county rental registry.
• Health permit. Three or more non-owner-occupied units generally need an Environmental Health permit and multi-unit inspections.

Water, septic and older buildings

Water. The Inverness Public Utility District serves 519 connections over about 2.5 square miles, using springs and streams off Inverness Ridge. Its regulations include separate rules for multiple service connections and water shortage emergencies. Marin LAFCo’s West Marin review urged IPUD to look at more storage for drought. Ask IPUD whether an added unit needs a separate connection.

Septic. There is no sewer. Septic capacity, soils and setbacks from Tomales Bay and creeks are usually the limit on adding units. Enlarging a septic system can itself trigger a coastal permit.

Fire. IPUD’s volunteer fire department serves the village; hillside homes on Inverness Ridge are in heavy forest, so confirm defensible space and insurance early.

Older buildings. Many homes predate modern codes. Consider a seismic retrofit check, and for three or more units with elevated decks, SB 721 inspections.

Coastal permits and the Inverness village

Inverness has its own policy section and historic area map in the county’s 2019 certified LCP Land Use Plan, which the Board adopted in 2018 and the Coastal Commission certified on February 6, 2019. The ridge neighborhoods also fall under the county’s 1983 Inverness Ridge Communities Plan. For an investor, three practical points follow. First, a unit built without a coastal permit is a compliance problem even if a building permit exists, so ask for both. Second, coastal permit decisions for some uses can be appealed to the Coastal Commission, which adds time to any expansion. Third, parcels next to Tomales Bay need extra biological information for coastal permits under the LUP’s shoreline policy, so a bayside duplex addition will cost more to entitle than an inland one.

Underwriting an Inverness multifamily purchase

1. Confirm the coastal district and that each unit has a permit, including coastal permits.
2. Get IPUD water service records and any multiple-connection approvals.
3. Get septic permits and capacity from county Environmental Health.
4. Separate long-term rent from STR income, and verify which STR licenses exist and whether they renew.
5. Classify tenancies under AB 1482 and the county just cause rule, and collect estoppel certificates.
6. Model insurance, septic reserves and taxes in our rental property analysis.

Questions people ask

Sources & notes

1. Marin County Coastal Zoning Code Ch. 20.62
2. Marin County, Law CDP P6327
3. Marin County, West Marin housing element sites
4. Marin County renter pages: Just Cause, Mandatory Mediation
5. Marin County: STR administrative procedures, business license, multi-unit inspection
6. Inverness PUD: About, water regulations
7. Marin County 2019 certified LCP Land Use Plan
8. Marin LAFCo, West Marin MSR, March 2022 draft
9. California Attorney General, Rent Caps

Note: We did not confirm which districts are mapped in Inverness or read IPUD regulation text.

General information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

Related: Inverness real estate guide · Commercial real estate in Inverness · Multifamily investing guide · Investor services