Can You Serve Someone by Mail in California? Section 415.30 Rules

Yes, you can serve someone by mail in California, but the mailing only counts as service if the recipient signs and returns an acknowledgment form. The procedure lives in California Code of Civil Procedure Section 415.30, and it hinges entirely on the other side’s cooperation. If they sign, service is complete. If they ignore the envelope, nothing has happened and you’ll need to serve them a different way.¹

How Mail Service Works Under Section 415.30

Service by mail is not the same as dropping lawsuit papers in a mailbox. You send the defendant a packet that includes the summons, the complaint, and a specific acknowledgment form. From the date of mailing, the defendant has 20 days to sign the form and send it back. If they do, service is complete as of the date they signed. If they don’t, the attempt fails.¹

That is the trap most people miss. Unlike personal delivery or substituted service, the defendant holds all the leverage. They can toss the envelope and face no immediate consequence. Many attorneys still try mail first because it costs almost nothing, but they always have a backup ready.

Don’t confuse this with substituted service, which also involves a mailing step. Substituted service under Section 415.20 requires someone to first leave papers with a competent person at the defendant’s home or workplace, then mail a second copy. That method does not require the defendant’s cooperation.

What Goes in the Envelope

The mailing has to include all of the following:

A copy of the summons and the complaint.
Two copies of the Notice and Acknowledgment of Receipt form (POS-015). The sender fills in the case caption and court information before mailing. The defendant signs one copy and keeps the other.²
A prepaid return envelope addressed to the sender, so the defendant can mail the signed form back at no cost to themselves.

Everything goes out by first-class mail or airmail with postage fully paid. Certified mail and signature confirmation are not required for this method.¹

Who Can Send It

Anyone at least 18 years old who is not a party to the lawsuit can mail the packet. If you are the plaintiff, you cannot mail it yourself. A friend, relative, coworker, or professional process server all qualify, as long as they meet both requirements.³

The 20-Day Window

Once the packet is in the mail, you wait. Two things can happen.

If the signed form comes back, service is officially complete on the date the defendant signed it. The person who did the mailing then fills out a Proof of Service of Summons, attaches the signed acknowledgment, and files everything with the court.⁴

If nothing comes back within 20 days, the mail attempt has failed and you have to serve the defendant some other way. There is one consolation. You can ask the court to order the defendant to pay the costs of whatever alternative method you end up using. That cost-shifting provision exists specifically to discourage people from ignoring the acknowledgment.¹

The Defendant’s Response Deadline

Once service is complete, the defendant has 30 days to file a written response to the complaint. The summons itself states this in both English and Spanish.⁵ That clock starts on the date the defendant signed the acknowledgment, not the date you mailed the packet. If no response is filed in time, you can ask the court to enter a default judgment.

What to Do When Mail Service Fails

Because everything depends on the defendant signing, have a backup ready. California recognizes several other methods.

Personal Service

The most reliable option. Someone physically hands the summons and complaint to the defendant, and service is complete the moment the documents change hands. Courts rarely question its validity because nothing about it depends on the defendant’s cooperation.⁶ If you tried mail service first and were ignored, ask the court to make the defendant reimburse what you paid the process server.

Substituted Service

If the defendant is dodging personal delivery, the server can leave the documents with a competent adult at the defendant’s home, workplace, or usual mailing address, then mail a second copy by first-class mail, Priority Mail with tracking, or certified mail. Service is considered complete 10 days after that mailing, whether or not the defendant picks up the papers.⁷ Courts expect to see reasonable diligence in attempting personal delivery before you fall back on this method.

Service by Publication

A last resort for situations where you truly cannot locate the defendant. You publish the summons in a newspaper, and the court must approve the method in advance. Judges grant these orders only after you show that personal delivery, substituted service, and other methods are all impractical.

Serving a Business by Mail

Section 415.30 works for corporations and other business entities, not just individuals. The acknowledgment form includes language for corporate recipients, and someone authorized by the entity has to sign on its behalf.¹

The documents have to reach someone with authority to accept service, such as the company’s registered agent for service of process, the president, CEO, vice president, secretary, treasurer, general manager, or another person the entity has designated.⁸ Every corporation registered in California must designate an agent with the Secretary of State, and you can look up that agent for free through the Secretary of State’s online business search.

Federal Cases and Defendants Abroad

Section 415.30 governs California state court cases. If your case is in federal court, a different rule applies. Under Federal Rule of Civil Procedure 4(d), the plaintiff sends the defendant a formal request to waive service of summons. A domestic defendant has at least 30 days to return the waiver, and 60 days if located abroad. A domestic defendant who refuses without good cause must be ordered to pay the costs of formal service and the attorney’s fees spent collecting those costs. Believing the suit is frivolous or filed in the wrong court is not good cause.⁹

If the person you need to serve lives in another country, the Hague Service Convention may govern. Mail service is permitted only if the destination country has not objected and the forum’s law authorizes it. Several countries have objected, including China, Germany, India, Mexico, South Korea, and Russia. For those destinations, mail service is off the table regardless of what California or federal rules would otherwise allow, and you generally have to route the request through the country’s Central Authority. That process can take months.¹⁰

1
California Legislative Information. California Code of Civil Procedure Section 415.30
2
California Judicial Branch. Notice and Acknowledgment of Receipt – Civil (POS-015)
3
California Legislative Information. California Code of Civil Procedure Section 414.10
4
Justia Law. California Code of Civil Procedure Article 5 – Proof of Service
5
California Legislative Information. California Code of Civil Procedure Section 412.20
6
Justia Law. California Code of Civil Procedure Section 415.10
7
California Legislative Information. California Code of Civil Procedure Section 415.20
8
California Legislative Information. California Code of Civil Procedure Section 416.10
9
Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
10
U.S. Department of Justice. OIJA Guidance on Service Abroad in U.S. Litigation