Your Kids Can't Buy Here. You Have a Lot.

Your son is thirty-one, married, has a two-year-old, and makes decent money. He cannot buy a house in this county. Not a starter house, not a fixer in a marginal neighborhood — nothing. He'll rent until he's forty-five, or he'll move to Boise.

You've probably already run this math and concluded there's nothing to do about it. There is. It's sitting in your back yard.

What your parcel can actually hold

California law now lets most single-family lots carry two additional homes.

An accessory dwelling unit (ADU) is a full, independent residence — detached in the back yard, attached to the house, or converted from a garage — with its own kitchen and bathroom.

A junior accessory dwelling unit (JADU) is a second, smaller unit carved out of the existing house, capped at 500 square feet, with an efficiency kitchenette rather than a full kitchen, and limited to one per single-family lot.

One house. Three households. Your son, his wife and the grandchild in the detached unit out back; your daughter in the junior unit off the side of the house.

The rules stopped fighting you

There is no owner-occupancy requirement for a standard ADU in California, and local agencies are prohibited from imposing one. That prohibition used to sunset. Assembly Bill 976 made it permanent.

The junior unit is where 2026 matters. Assembly Bill 1154, effective January 1, 2026, introduced a bathroom-based distinction: if the JADU has its own separate bathroom, owner-occupancy is no longer required, and both the main home and the junior unit can be rented while the owner lives elsewhere. Share sanitation facilities with the main house and the owner still has to live on the property. Junior unit rentals must also run longer than 30 days.

Read that again, because it is a decision you make at the drafting table. A separate bathroom in the junior unit costs you some money now and buys the next generation the ability to rent every unit on the parcel. A shared bathroom saves the money and chains the arrangement to somebody living there. Both can be right. Neither should be an accident.

What it costs

A junior unit typically runs $50,000 to $100,000 — less than half a detached ADU — because it sits inside existing walls with no new foundation, no new roof and no utility trenching. Junior units are also exempt from development impact fees and school fees, the two line items that add $10,000 to $25,000 to a standard ADU permit.

A garage conversion generally runs $70,000 to $120,000. A new detached unit costs materially more.

Get real bids on your own lot before you plan around any of these numbers. Site conditions, utility runs and setbacks decide the price, not a published range.

What it does to your property tax

New construction gets assessed. The base year value on the house you bought in 1984 does not move.

You are adding an assessment for the new unit. You are not surrendering the one you have been protecting for forty years. That is the single most misunderstood point in this entire subject, and it is the reason a lot of owners never get past the first phone call.

What it costs you that nobody mentions

Building an ADU can strip the single-family exemption from state rent cap law before you ever sign a lease. That is a real consequence with real dollars attached, and it is covered in full in The ADU Decision, Part 1.

This is the least interesting part

Housing your kids is the reason you will start. It is not the reason this is worth doing.

The return shows up in fifteen years, when you are the one who needs help getting to an appointment. And again at the end, when the parcel transfers.

Those are Parts 2 and 3.

A note on timing: the rules underneath this article are moving. California's accessory dwelling unit statutes were recodified into Government Code sections 66310 through 66342 effective January 1, 2025, so older articles cite repealed sections. Junior unit occupancy rules changed on January 1, 2026. Everything here reflects what I could verify as of the date on this post, and none of it is legal, tax or accounting advice. Before you build, transfer, or restructure anything, take your specific facts to an estate planning attorney and your certified public accountant. I manage property; I don't practice law and I don't prepare returns.