Roommate laws in California turn on one question: which of the three legal categories does your arrangement fall into? Co-tenants share a lease and share equal rights and equal exposure. A subtenant rents from another tenant, not the property owner. A lodger rents a room in an owner-occupied home. The category controls how rent liability works, whether you can recover your deposit share when you leave, how much notice ends the arrangement, and how hard it is to remove someone who won’t go.
The Three Categories That Decide Everything
If you and your roommates all signed the same lease with the landlord, you’re co-tenants. Each of you has an equal right to occupy the whole unit, and each of you is independently responsible to the landlord for the lease terms. No co-tenant has authority over another. Disputes between you are private matters the landlord has no duty to referee.
A subtenant relationship works differently. One person, the master tenant, holds the lease with the landlord and then rents part of the unit to someone else. The subtenant’s legal relationship runs to the master tenant, not the property owner. The master tenant effectively acts as a landlord to the subtenant and must follow California’s landlord-tenant laws when dealing with that person.
A lodger occupies a room in a home where the owner also lives and keeps access to the entire dwelling. California Civil Code Section 1946.5 governs this arrangement, but only when a single lodger lives in the owner-occupied home.1California Legislative Information. California Code 1946.5 – Hiring of Real Property A single lodger has fewer protections than a standard tenant: the owner can terminate with written notice and doesn’t need to file an eviction lawsuit if the lodger overstays. Once a second lodger moves in, the streamlined removal process no longer applies and the owner has to use the court eviction process like any other landlord.
Who Owes the Rent
Co-tenants on the same lease face joint and several liability. The landlord can collect the entire amount from any one tenant if the others don’t pay. It doesn’t matter that you privately agreed to split $3,000 rent three ways. If your two roommates stop paying, the landlord can demand the full $3,000 from you alone and start eviction proceedings against the whole unit if you can’t cover it.
The same principle often extends to utility accounts listed under all tenants’ names. If one roommate skips out on the electric bill, the utility company can pursue any account holder for the full balance. Whoever pays more than their share can seek reimbursement from the others, usually in small claims court, but collecting from someone who wouldn’t pay in the first place is rarely easy.
A subtenant’s exposure is different. The subtenant owes rent to the master tenant, not the landlord. If a subtenant stops paying, the master tenant still owes the full rent to the landlord and has to handle the subtenant’s nonpayment separately. Being a master tenant carries the financial risk of both the lease and the sublease.
The Security Deposit When One Roommate Leaves
California caps security deposits at one month’s rent for most residential tenancies. This limit took effect in 2024 under AB 12, which amended Civil Code Section 1950.5.2California Legislative Information. California Code Civil Code 1950.5 – Security Landlords who are natural persons, or LLCs made up entirely of natural persons, and who own no more than two rental properties with four or fewer total units can charge up to two months’ rent. That exception doesn’t apply if the prospective tenant is a service member.
When one roommate moves out but the lease continues, the landlord generally has no obligation to return any portion of the deposit. Section 1950.5 ties the return obligation to the termination of the entire tenancy, not the departure of individual occupants.2California Legislative Information. California Code Civil Code 1950.5 – Security The departing roommate’s realistic option is negotiating with the remaining tenants for reimbursement of their share. This is one of the most common roommate disputes in California and the strongest argument for putting deposit-split terms in writing before anyone moves in.
Guests, Occupancy, and Choosing a Roommate
Every California tenant has a right to quiet enjoyment of their rental, which includes having guests over without unreasonable interference from the landlord or other tenants.3California Legislative Information. California Code CIV 1927 Guests and occupants are different categories though, and the line matters.
No California statute sets a specific number of days after which a guest automatically becomes a tenant. The commonly cited “14 days in six months” or “7 consecutive nights” thresholds are lease provisions, not state law. Landlords include these limits to define when a guest’s stay triggers a lease violation, and courts look at the totality of the circumstances: whether the person receives mail there, keeps belongings in the unit, has a key, or contributes to household expenses. If your lease has a guest policy, treat those numbers as the standard for your tenancy.
For overall occupancy, California’s Department of Civil Rights uses an informal guideline of two people per bedroom plus one additional person for the whole unit.4California State Legislature. AB 616 Assembly Bill – Bill Analysis Under that standard, a two-bedroom apartment would have a suggested maximum of five occupants. Landlords can set stricter limits in the lease, but the limits must have a legitimate basis. Using occupancy restrictions as a pretext for family-status discrimination violates fair housing law.
Fair housing rules also shape how you advertise for a roommate. If you’re looking for someone to share a bathroom or kitchen, you can state a same-gender preference for privacy reasons. You cannot advertise cross-gender preferences or tie housing terms to intimate relationships. And you cannot discriminate based on race, religion, or national origin under any circumstances, even in owner-occupied shared housing.
Just Cause Protections Often Don’t Apply
The California Tenant Protection Act (AB 1482, codified as Civil Code Section 1946.2) requires landlords to have just cause before terminating a tenancy once the tenant has lived in the unit for at least 12 months.5California Legislative Information. California Civil Code 1946.2 Just cause covers fault-based reasons like not paying rent or violating the lease, and no-fault reasons like the owner moving in or withdrawing the unit from the market.
Several exemptions cut directly against typical roommate arrangements:
- Rooms in an owner-occupied home where you share a bathroom or kitchen with the owner aren’t covered.
- Owner-occupied single-family homes where the owner rents out no more than two bedrooms or units, including ADUs, aren’t covered.
- Owner-occupied duplexes are exempt if the owner lived in the unit when the tenancy began and continues to live there.
If you’re renting a room from a live-in homeowner, don’t assume the just cause rules protect you. Check whether your situation fits one of these carve-outs before treating the TPA as a defense against a termination notice.
Ending a Roommate’s Tenancy
Under Civil Code Section 1946.1, a property owner or master tenant must give at least 60 days’ written notice to terminate a month-to-month tenancy if the occupant has lived in the unit for a year or more. If the occupant has been there less than a year, 30 days is enough.6California Legislative Information. California Code Civil Code 1946.1 – Termination of Periodic Tenancy A tenant giving notice to end their own month-to-month tenancy only needs to give 30 days regardless of how long they’ve been there.
Co-tenants on the same lease face a harder problem. One co-tenant generally cannot evict another, because both have equal rights under the lease. Only the landlord can terminate a co-tenant’s occupancy. If you want a co-tenant gone, you typically have to involve the landlord, which may mean the landlord terminates the entire lease and offers a new one that excludes the unwanted roommate. Where the Tenant Protection Act applies, even that route requires just cause.
Serving the Notice Correctly
California requires termination notices to be delivered by specific methods to be legally valid. Personal service, meaning handing the notice directly to the person, is the most straightforward. If the person can’t be found, substituted service lets you leave the papers with another adult at the residence and then mail a copy to the same address.7California Courts | Self Help Guide. Serve Your Lawsuit by Substituted Service
When neither the roommate nor another suitable adult can be found, California Code of Civil Procedure Section 1162 allows a “post and mail” method: attach a copy of the notice to a visible spot on the property and mail another copy to the tenant at the property address.8California Legislative Information. California Code CCP 1162 This method adds days to the notice period, typically five for mailing, so build that into your timeline.
When a Roommate Refuses to Leave
If a roommate stays past the notice deadline, you cannot change the locks, shut off utilities, remove their belongings, or take any other physical step to force them out. California Civil Code Section 789.3 makes self-help evictions illegal and imposes real penalties: actual damages plus up to $100 per day the violation continues, with a minimum award of $250 per violation. The court also awards attorney’s fees to the prevailing tenant.9California Legislative Information. California Civil Code 789.3
The legal path is filing an unlawful detainer lawsuit, California’s formal eviction process. The landlord (or master tenant, in a subtenancy) files the case, the roommate is served with court papers, and the roommate has five days to respond. Without a response, the landlord can ask for a default judgment. With a response, the case goes to trial, typically within about 20 days.10California Courts | Self Help Guide. Eviction Cases in California Even straightforward cases take several weeks from filing to actual removal.
A co-tenant trying to remove another co-tenant faces an added obstacle. You likely can’t file the unlawful detainer yourself because you’re not the landlord. You’ll need the landlord’s involvement, or you may have to pursue the dispute through a different legal channel.
Tax on Rent You Collect from a Subtenant
If you’re a master tenant collecting rent from a subtenant, the IRS treats those payments as rental income you have to report. Being a renter yourself doesn’t exempt you from reporting what someone pays you for space in your unit.11Internal Revenue Service. Rental Income and Expenses If your subtenant pays any of your expenses directly, like covering a utility bill, that counts as rental income too.
You can deduct a proportional share of rental expenses against that income: the portion of rent, utilities, and renter’s insurance attributable to the space the subtenant occupies. Keep records of every payment received and every expense you plan to deduct. The IRS failure-to-file penalty starts at 5% of the unpaid tax per month, capping at 25%. Returns filed more than 60 days late trigger a minimum penalty of $525 or 100% of the tax owed, whichever is less.12Internal Revenue Service. Failure to File Penalty
Co-tenants who split rent equally and pay the landlord directly generally don’t have this issue, because no one is collecting rent from anyone else. Everyone is paying their own obligation. The reporting requirement kicks in when one person receives housing payments from another.
Put It in Writing Before Anyone Moves In
A lease governs the relationship between tenants and the landlord. It usually says nothing about how roommates split costs, handle guests, or manage the security deposit when one person leaves. A separate written roommate agreement fills that gap. Courts won’t enforce every provision, since you can’t contract around someone’s legal rights as a tenant, but financial and practical terms are generally enforceable as a private contract: who pays what share of rent and utilities, how much notice to give before moving out, how the security deposit gets divided.
The most useful thing a roommate agreement does is settle the deposit question before it becomes a fight. When one person leaves, the remaining roommates rarely want to reimburse the departing roommate’s share out of pocket, and the landlord has no obligation to return anything until everyone is gone. A written agreement that spells out how the outgoing roommate gets repaid, whether by the replacement or by the remaining tenants within a set number of days, prevents the single most common source of roommate litigation in the state.