Proof of service by mail may be made by one of the following methods:
§ 1013a.Proof of Mail Service
Title 14. Of Miscellaneous Provisions · Chapter 5. Notices, and Filing and Service of Papers · Last amended 1996 · Last verified July 28, 2026
In one sentenceSection 1013a lists the ways to prove service by mail -- a sworn affidavit, a State Bar member's certificate, an affidavit describing regular business mailing practice, or a court clerk's certificate -- each requiring the server's identity, the date and place of mailing, and the recipient's name and address.
Full Text of § 1013a
(1) An affidavit setting forth the exact title of the document served and filed in the cause, showing the name and residence or business address of the person making the service, showing that he or she is a resident of or employed in the county where the mailing occurs, that he or she is over the age of 18 years and not a party to the cause, and showing the date and place of deposit in the mail, the name and address of the person served as shown on the envelope, and also showing that the envelope was sealed and deposited in the mail with the postage thereon fully prepaid.
(2) A certificate setting forth the exact title of the document served and filed in the cause, showing the name and business address of the person making the service, showing that he or she is an active member of the State Bar of California and is not a party to the cause, and showing the date and place of deposit in the mail, the name and address of the person served as shown on the envelope, and also showing that the envelope was sealed and deposited in the mail with the postage thereon fully prepaid.
(3) An affidavit setting forth the exact title of the document served and filed in the cause, showing (A) the name and residence or business address of the person making the service, (B) that he or she is a resident of, or employed in, the county where the mailing occurs, (C) that he or she is over the age of 18 years and not a party to the cause, (D) that he or she is readily familiar with the business' practice for collection and processing of correspondence for mailing with the United States Postal Service, (E) that the correspondence would be deposited with the United States Postal Service that same day in the ordinary course of business, (F) the name and address of the person served as shown on the envelope, and the date and place of business where the correspondence was placed for deposit in the United States Postal Service, and (G) that the envelope was sealed and placed for collection and mailing on that date following ordinary business practices. Service made pursuant to this paragraph, upon motion of a party served, shall be presumed invalid if the postal cancellation date or postage meter date on the envelope is more than one day after the date of deposit for mailing contained in the affidavit.
(4) In case of service by the clerk of a court of record, a certificate by that clerk setting forth the exact title of the document served and filed in the cause, showing the name of the clerk and the name of the court of which he or she is the clerk, and that he or she is not a party to the cause, and showing the date and place of deposit in the mail, the name and address of the person served as shown on the envelope, and also showing that the envelope was sealed and deposited in the mail with the postage thereon fully prepaid. This form of proof is sufficient for service of process in which the clerk or deputy clerk signing the certificate places the document for collection and mailing on the date shown thereon, so as to cause it to be mailed in an envelope so sealed and so addressed on that date following standard court practices. Service made pursuant to this paragraph, upon motion of a party served and a finding of good cause by the court, shall be deemed to have occurred on the date of postage cancellation or postage meter imprint as shown on the envelope if that date is more than one day after the date of deposit for mailing contained in the certificate.
Plain-English Summary
Once papers go out by mail under § 1013, someone eventually has to prove it happened. This section lists four acceptable ways to do that. The first is an affidavit from the person who mailed the documents, showing their name and address, that they're a resident of or employed in the county of mailing, that they're over eighteen and not a party to the case, and the date, place, and details of the mailing. The second substitutes a certificate for the affidavit when the person mailing the documents is an active member of the State Bar of California.
The third method accommodates offices with routine mailing systems: an affidavit describing the business's ordinary practice for collecting and processing mail, showing the correspondence would have gone out that same day in the ordinary course of business. That method comes with a built-in check — if the postal cancellation or postage meter date on the envelope is more than one day after the deposit date the affidavit claims, service made this way is presumed invalid on a served party's motion. The fourth method lets a court clerk certify service the same way, with a parallel rule letting the court find, for good cause, that service occurred on the postmark date if it's more than a day later than the certificate states.
Frequently Asked Questions
What are the accepted ways to prove service by mail?
An affidavit from the person who mailed the papers, a certificate from an active State Bar member, an affidavit describing the mailer's ordinary business practice, or a certificate from the court clerk.
What must the affidavit or certificate include?
The exact title of the document, the server's name and address, confirmation the server is over eighteen and not a party, and the date, place, and recipient details of the mailing.
What happens if the postmark date doesn't match the stated mailing date under the business-practice method?
Service is presumed invalid, on motion of the party served, if the postal cancellation or postage meter date is more than one day after the deposit date stated in the affidavit.
Amendment History
Amended by Stats. 1995, Ch. 576, Sec. 4. Effective January 1, 1996.
Source & verification. Section text is reproduced verbatim from
the Deering's California Codes Annotated / vLex. Enacted by the California Legislature.
Last verified July 28, 2026.
· Official source
Also known as: proof of service by mail californiaaffidavit of mailing california