Proof of service in a California unlawful detainer case is the sworn document showing the court that the tenant received the summons and complaint in a legally valid way. Without it on file, the case cannot move to default, hearing, or judgment. The proof is filed on Judicial Council Form POS-010, signed by the person who did the service, and it must accurately describe one of three service methods authorized by the Code of Civil Procedure.
Who Can Serve the Papers
Any person at least 18 years old who is not a party to the lawsuit can serve the summons and complaint.1California Legislative Information. California Code of Civil Procedure CCP 414.10 The landlord is a party and cannot hand the papers to the tenant. Most landlords use a registered process server or the county sheriff. A friend or relative who meets the age requirement can also serve the documents, though proof of service filed by a professional server or law enforcement officer tends to carry more weight if it is later challenged.
One document has a stricter rule. If the landlord is also serving a prejudgment claim of right to possession on unnamed occupants, only a marshal, sheriff, or registered process server can perform that service.2California Legislative Information. California Code of Civil Procedure CCP 415.46
The Three Ways to Serve the Summons and Complaint
California recognizes three methods. Each has to be executed correctly, and the proof of service must match what actually happened.
Personal Delivery
Handing the summons and complaint directly to the tenant is the cleanest option. Under CCP 415.10, service is complete the moment the documents are delivered.3California Legislative Information. California Code of Civil Procedure – Manner of Service of Summons The server records the date, time, and location. If the tenant refuses to take the papers, the server can set them down in the tenant’s presence and identify what they are; that still counts as valid personal service.
Personal delivery is the fastest route because it starts the tenant’s response clock immediately and leaves the least room for later argument about notice.
Substituted Service
When the tenant cannot be found after reasonable attempts, the server can leave the documents with another responsible adult at the tenant’s home or workplace. The person accepting the papers must be at least 18, and the server must explain what the documents are. A copy is then mailed by first-class mail to the tenant at the same address.3California Legislative Information. California Code of Civil Procedure – Manner of Service of Summons Service is deemed complete ten days after mailing.
Courts expect proof that personal service was tried first. A detailed log of each attempt, with dates, times, and what happened at the door, is what protects substituted service against a challenge. Thin documentation is where landlords most often get tripped up, because a tenant contesting service will argue the landlord did not try hard enough to reach them in person.
Posting and Mailing
When neither personal nor substituted service works, the landlord can ask the court for permission to post the summons and complaint on the rental property and mail a copy by certified mail to the tenant’s last known address. This method, sometimes called “nail and mail,” requires a sworn statement showing that reasonable efforts to serve the tenant by other means were unsuccessful.4California Legislative Information. California Code of Civil Procedure CCP 415.45 The court must be satisfied that the tenant is either avoiding service or cannot be located. If approved, service is complete on the tenth day after posting and mailing. Because this method offers the weakest guarantee that the tenant saw the papers, judges look at it closely, and a thorough record of failed attempts should accompany the request.
Unnamed Occupants in the Unit
If people are living in the property who are not named in the complaint and the landlord wants them bound by the judgment, a prejudgment claim of right to possession must be served alongside the summons and complaint. This is separate from serving the named tenant and carries its own rules under CCP 415.46.2California Legislative Information. California Code of Civil Procedure CCP 415.46
When serving the named tenant, the process server must ask whether other adults live in the unit. Any identified adult occupant who is present gets a copy of the prejudgment claim along with the summons and complaint. If that person cannot be served in person, the server can leave the documents with a responsible adult at the premises, post them in a visible spot on the property, and mail a copy by first-class mail. For unknown occupants, the server posts a copy of the prejudgment claim addressed to “all occupants in care of the named tenant” and mails it to the property.
Only a marshal, sheriff, or registered process server can handle service of the prejudgment claim. Skipping this step means unnamed occupants can file their own claims after judgment and delay the eviction.
What POS-010 Has to Show
Once service is done, the person who delivered the documents completes Judicial Council Form POS-010, Proof of Service of Summons. It is a mandatory form and tells the court who was served, when, where, and how.5California Courts. Proof of Service of Summons (POS-010) It is filled out and signed by the server, not by the landlord or the landlord’s attorney.
The server signs under penalty of perjury. A sheriff or marshal certifies the form rather than signing a perjury declaration.6Judicial Council of California. Judicial Council of California Form POS-010 – Proof of Service of Summons Falsifying the form can lead to sanctions, dismissal, or criminal liability.
For substituted service or posting and mailing, back the proof up with evidence of the effort to reach the tenant in person. A dated log of every attempt, postal receipts from any required mailings, and, where posting was used, photographs of the posted documents on the property all strengthen the filing against a later challenge.
Filing the Proof with the Court
The completed POS-010 gets filed with the superior court in the county where the rental property sits. Until it is in the file, the court will not move the case forward. No proof of service means no default, no hearing, and no judgment for possession.
Filing can be done in person at the clerk’s office, by mail, or through the court’s electronic filing system. Most California superior courts now accept e-filing and some require it. Filing the proof itself typically does not carry a separate fee. The clerk reviews the form for completeness before accepting it, so errors in dates, addresses, or the description of the service method can cause rejection. An amended form is possible if a mistake is caught later, but that adds time to a case built for speed.
File as soon as possible after service. The dates on this form drive the tenant’s response deadline, and any delay in filing pushes back the whole timeline.
When the Tenant’s Response Clock Starts
A properly served tenant has ten days to respond, not counting Saturdays, Sundays, or court holidays. The clock starts from the date service is deemed complete. For personal delivery, that is the day the tenant received the papers. For substituted service, service becomes effective ten calendar days after the mailing, and the ten court days run from that point. For posting and mailing, the starting point is the tenth day after posting and mailing. A tenant served through the Secretary of State’s address confidentiality program gets an additional five court days beyond the standard ten.7California Legislative Information. California Code of Civil Procedure CCP 1167
If the deadline passes without a response, the landlord can request entry of default using Judicial Council Form CIV-100. That request must include a declaration confirming a copy was mailed to the tenant’s last known address.8Judicial Council of California. CIV-100 Request for Entry of Default
What Happens If Service Is Done Wrong
Defective service does more than slow the case. If the court identifies a service defect at any point, it halts the proceedings until the tenant is properly served. The landlord pays for re-service and any additional filing fees and keeps losing rental income while the timeline stretches.
The bigger risk lands after a default judgment. A tenant who never actually received notice of the lawsuit can move to set aside the default under CCP 473.5, provided they act within two years of the judgment or 180 days after learning about it, whichever comes first.9California Legislative Information. California Code of Civil Procedure CCP 473.5 – Motion to Set Aside Default for Lack of Actual Notice If the court agrees, it vacates the judgment and the case essentially restarts. Any eviction carried out under a vacated judgment is unauthorized, and a tenant removed on that basis may have grounds to sue for wrongful eviction. Everything downstream of the proof of service depends on the service itself being clean.