What insurance covers a California duplex you live in?

Yes, as long as you live in one of the units. Living in one unit and renting out the others is often called house hacking. Insurers can build their homeowners policies on the HO-3, a model form from the Insurance Services Office (ISO).

Its 2011 edition defines the home it covers to include "the two-, three- or four-family dwelling where you reside" in one of the units. So one policy covers the whole building, both your unit and the rented one.

Insure the building for what it would cost to rebuild all of it. The Department of Insurance's guide says that amount "may have nothing to do with the purchase price or the current market value of your home."

Your insurer's own policy and rules decide in the end. Tell it how many units the building has before it quotes, and get its answer in writing.

If you later move out and rent every unit, the policy usually has to change to a landlord policy.

The building is covered, and so is lost rent. The 2011 form pays the "fair rental value" of a rented unit that covered damage leaves "not fit to live in," minus costs that stop.

That payment shares one limit with your own extra living costs. The Department of Insurance's guide says loss-of-use coverage is "normally limited to 20 percent of Coverage A," the rebuild amount.

Your own appliances, carpet and furniture in the rented unit get a small allowance. The form pays up to $2,500 for them in each rented apartment, but not for theft.

Theft from the rented unit is not covered, even of your own things there.

Your tenant's belongings are not covered either. The form lists "property of roomers, boarders and other tenants" among the property it does not cover.

So ask your tenant to carry a renters policy. The Department of Insurance's guide says one covers a renter's "personal contents" where they live.

Under the model form, generally yes. Its liability section covers injuries you are legally responsible for. Its business exclusion also makes an exception for renting part of the property "for use only as a residence."

The form's medical payments coverage is different. It pays a guest's medical bills whoever is at fault, but not the bills of anyone who lives on the property, a tenant included.

Your tenant's own liability belongs on their renters policy, which the same guide says includes "personal liability protection."

Ask what liability limit your policy carries, and whether a higher one is available.

It can. House hacking can also mean renting rooms inside the unit you live in. The model form's liability exception ends where one unit houses "more than two roomers or boarders."

So tell your insurer before a third roomer moves in. Each roomer's belongings are theirs to insure, the same as a tenant's.

Short stays are a different matter. Paying guests raise their own questions, covered in how homeowners policies treat Airbnb guests.

Some homes on a two-unit lot cannot be rented short term at all. Government Code Section 65852.21 lets many single-family lots get two homes approved without a hearing. For a unit built that way, a city or county must require rentals "for a term longer than 30 days."

If standard insurers say no, the Department of Insurance's guide points to the "surplus lines" market. Those are specialty insurers, reached through a licensed agent or broker.

The FAIR Plan comes last. Its dwelling page lists owner-occupied "1-4 unit dwellings in which the owner lives in one or more unit." Its online calculator lets you pick a duplex, triplex or four-plex.

Under the Plan's 2021 rules, an owner-occupied building with any part "rented out for less than 365 days" was "rated as a short-term rental." If your tenant's lease runs under a year, ask the Plan in writing how it rates your building.

A FAIR Plan policy covers fire and smoke, plus wind and hail if you add them. It does not cover water damage from a burst pipe, theft, or someone getting hurt on your property.

Liability is the gap to watch with a tenant next door. While you are on the FAIR Plan, keep shopping for one full homeowners policy that covers the whole building.

California's non-renewal rule covers homes of "not more than four dwelling units," a duplex included. If it will not renew, your insurer must mail or hand you notice at least 75 days (90 days beginning January 1, 2028) before your policy's end date.

Give these answers in writing, and ask for the insurer's replies in writing too:

• How many units the building has, and which one you live in.
• Whether tenants live in the other units, and on what lease terms.
• The cost to rebuild the whole building, not what you paid for it.
• Any rooms you rent inside your own unit, and how many roomers live there.
• Any unit rented for short stays, even a few weekends a year.
• The appliances and furniture you provide in each rented unit.
• The liability limit you want the quote to include.