Multifamily and Duplex Properties for Sale in Dillon Beach: Zoning and Rent Rules

What multifamily in Dillon Beach looks like

Dillon Beach has almost no apartment buildings. Investment property here is mainly single-family homes, some with a legal ADU or a second unit, in the old village and the Oceana Marin subdivision. Many are vacation rentals, and agricultural parcels may carry farmworker or caretaker units. The village lots are among the smallest in Marin, so "multifamily" means adding a unit where wastewater, parking and coastal rules allow, not building a complex. Two- to four-unit buyers should see financing 2-4 unit properties, and for any larger holding, apartment building loans.

Where the zoning allows it

Dillon Beach is unincorporated and entirely in the Coastal Zone. Zoning comes from the county’s coastal districts (Chapter 20.62), guided by the 1989 Dillon Beach Community Plan, which the Coastal Commission has certified as part of the LCP.

According to the county’s Dillon Beach background page, the village has 160 lots, 149 developed, typically about 1,725 square feet each. Most homes were built in the 1930s and 1940s on narrow streets. On lots that size, an ADU or JADU created inside the existing house is usually more realistic than a detached unit. See our ADU investment guide.

SB 9. SB 9 lot splits and two-unit projects are often unavailable on small coastal lots, in hazard areas or where services are inadequate. The Coastal Act process still applies. Confirm eligibility with the county before paying for upside, and see our SB 9 lot split guide.

Rent rules: state law plus Marin County’s just cause and mediation

Rent caps. The Attorney General’s rent cap page puts Marin in the San Francisco Area region. The maximum increase for covered units is 6.3% from August 1, 2025, and 8.8% from August 1, 2026 through July 31, 2027. There is no local cap. See our AB 1482 guide.

County just cause. Marin County’s just cause ordinance (Ordinance 3705, Chapter 5.100, adopted December 18, 2018) applies in unincorporated areas such as Dillon Beach. It covers lots with three or more dwelling units. Short-term rental and vacant units count toward the three, but permitted ADUs and JADUs are exempt. Most single homes with one ADU fall outside it, but a parcel with several cottages may not. See our just cause eviction guide.

Mediation. The county’s mandatory mediation program lets tenants require free mediation of increases over 5% in 12 months.

Dillon Beach rental property rules

• Short-term rentals. Under Chapter 5.41 (May 2024), Dillon Beach sits outside the 1,200-license countywide cap. It has its own cap of 125 licenses initially and 204 ultimately, the only township set to grow. Each owner may hold one license. New ADUs, deed-restricted units and multifamily units are ineligible unless they were legally operating as of January 1, 2024. Parking must meet county standards. A license transfers only under the county’s rules, so confirm what a sale does to it.
• Business license and TOT. Rental operators need a county business license, and stays of 30 days or less need a transient occupancy tax certificate.
• Transfer tax. Only the county’s $0.55 per $500 applies, per the Recorder’s sheet.

Septic, water and coastal hazards

Water in the village and part of Oceana Marin comes from Coast Springs Water Company, owned by Cal Water and regulated by the CPUC. The county notes the supply is vulnerable to septic contamination, surface infiltration and high mineral content, and that village use has shifted from seasonal to year-round. Village homes rely on septic, and Environmental Health runs a community wastewater program for Dillon Beach. Oceana Marin homes are on North Marin Water District’s sewer, which has 235 connections. Before adding a unit, confirm septic capacity or sewer service in writing. Older 1930s–40s cottages often need foundation, electrical and roof work, and a seismic retrofit review may be worthwhile. A building of three or more units with elevated decks would need SB 721 inspections.

Underwriting a Dillon Beach rental purchase

1. Confirm the coastal district, the legal unit count and the permit status of any second unit.
2. Identify the water provider and the sewer or septic system, and get records and an inspection.
3. Check whether the county’s just cause rule applies (three or more units) and classify each unit under AB 1482.
4. Separate STR income from long-term income, confirm the license status, and model what happens if a license does not survive the sale.
5. Collect leases, rent rolls and estoppel certificates for long-term tenants.
6. Rebuild expenses with reassessed taxes, insurance for coastal exposure and septic upkeep in our rental property analysis.

Questions people ask

Sources & notes

1. Marin County Code Ch. 20.62 and Ch. 5.41 (GoCodebook)
2. Marin County, Community and Area Plans and 2019 Certified LCP Land Use Plan
3. Marin County Environmental Health, Dillon Beach background
4. North Marin Water District, Oceana Marin Sewer
5. Marin County, Just Cause Eviction and Mandatory Mediation
6. California Attorney General, Rent Caps
7. Marin County Recorder, transfer tax and Business License

Note: We did not read the Dillon Beach Community Plan text or confirm whether any C-R2 or C-RMP land is mapped in Dillon Beach. Check the county zoning map.

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

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