POS-010 Proof of Service of Summons: Plain-English Guide

What this form actually does

Before a case can move forward against a defendant, that defendant has to be properly served with the summons and complaint. POS-010 is filed with the court as sworn proof of exactly how, when, and where service happened. Without a valid Proof of Service on file, the court won't let a case proceed against that defendant — including blocking a request for entry of default.

Who completes it

Whoever actually served the papers completes and signs this form — typically a registered process server, sheriff, or any adult who is not a party to the case and is over 18. The plaintiff generally cannot serve their own papers.

Filling it out, section by section

Case information. Match the case number and party names exactly to the filed complaint.
Documents served. List every document that was served along with the summons — the complaint, any attachments, and other required papers.
Person served. Name the individual served, and if serving a business or entity, the title of the person who accepted service on its behalf.
Method of service. Check the box matching how service happened: personal delivery, substituted service (leaving with someone else at the home/work with a mailed follow-up copy), service by mail with acknowledgment, or another approved method — each has its own specific requirements that must be met exactly.
Date, time, and address of service. Precise details, since these matter if service is ever challenged.
Server's declaration. The server signs under penalty of perjury (or, if a registered process server, certifies under the applicable business and professions code section).

Different methods, different timelines: substituted service isn't complete until a set number of days after the papers are also mailed to the person, and some methods require a Declaration of Due Diligence showing reasonable attempts at personal service first. Using the wrong method, or filing before it's actually complete, is one of the most common reasons defaults get challenged later.

Common mistakes

The plaintiff serving the papers themselves, which most courts don't allow.
Filing the Proof of Service before substituted service's mailing requirement has actually been completed.
Mismatched names — the person served doesn't match the named defendant, or a business is served without confirming the recipient was authorized to accept on its behalf.
Missing details like exact time or address that make the proof of service harder to defend if challenged.

After it's filed

Once a valid Proof of Service is on file, the clock starts on the defendant's time to respond. If that time passes without a response, the plaintiff can move forward with a Request for Entry of Default.