SB 9 in San Jose: can you split your lot or add a second home?

A few times a month a homeowner asks me some version of the same question: “Can I split my lot and sell the back half?” Since 2022 the answer in California is often yes, because of a state law called SB 9. It is also a law with more fine print than most people expect, so here is the short version for San Jose.

What SB 9 allows

On a lot zoned for a single family home, SB 9 lets you do one of two things, and the city has to review it by checklist rather than by public hearing:

• Build two homes on one lot. A duplex, or two separate houses.
• Split the lot in two, and put up to two homes on each new lot. That is up to four homes where there was one.

The state's housing department keeps a plain language summary: HCD's SB 9 fact sheet.

The rules that decide whether it works for you

• Lot size. Each new lot generally has to be at least 1,200 square feet, and the smaller lot can be no less than 40 percent of the original. The exact wording is in Government Code 66411.7.
• You have to live there. To split a lot you sign a statement that you plan to live in one of the homes as your main residence for three years. An investor or an LLC cannot use the lot split.
• One split only. A lot that was already split under SB 9 cannot be split again, and the same owner cannot split the lot next door.
• Some properties are out. Historic properties, homes with protected or rent controlled tenants, and certain hazard areas do not qualify.
• Size and setbacks. The city cannot hold you below 800 square feet per home, and side and rear setbacks can be as small as 4 feet.
• No short term rentals. Any home built under SB 9 has to be rented for more than 30 days at a time.

What changed recently

Since January 2025, cities have to approve or deny an SB 9 application within 60 days of it being complete, or it is treated as approved, and they can only apply the same objective standards they use for everything else in the zone. Since January 2026, a home inside a historic district is only excluded if the home itself is a contributing historic structure, instead of the whole district being off limits.

One thing that did not change: a 2026 bill that would have loosened the three year owner occupancy rule died in August. The rule stays.

How it looks in San Jose

San Jose accepts SB 9 projects in its single family zones (R-1 districts and some planned development zones). The city's pages explain the process and the checklists: about SB 9 in San Jose and how to apply for an SB 9 duplex or lot split.

Uptake has been real but modest. By March 2025 the city reported nearly 60 lot split applications and more than two dozen new homes and duplexes filed (City of San Jose). Most owners find that the numbers, not the rules, decide it: surveys, a parcel map, utilities, and construction on the new lot add up.

If you live near a major transit stop, a separate state law, SB 79, took effect in July 2026 and allows more homes near stations. San Jose's approach is on the city's SB 79 page.

Who it fits

SB 9 tends to work best for owners with a large or deep lot, good street access to the back, and a plan to stay at least three years. For a seller, it can also change what your home is worth to the right buyer, because a lot that can hold more homes appeals to a different kind of buyer.

If you are wondering whether your lot qualifies, send me the address. I will pull the lot size and zoning and tell you honestly whether it is worth a closer look, and when it is time for a surveyor or a land use attorney.

I am a REALTOR®, not an attorney or a planner. Sources: HCD SB 9 fact sheet, Government Code 66411.7, City of San Jose SB 9 and City of San Jose SB 79. Checked September 2026. Laws and city rules change, so confirm with the City of San Jose Planning Division before relying on anything here.