An Affidavit of Service (also called a Proof of Service or Certificate of Service) is a sworn legal document filed with a court to prove that legal documents -- such as a summons, complaint, motion, subpoena, or other pleading -- have been properly delivered to a party in a legal proceeding. This document is a fundamental component of due process, as guaranteed by the Fifth and Fourteenth Amendments to the U.S. Constitution, which require that parties to a legal action receive adequate notice and an opportunity to respond.

Service of process is governed by Federal Rule of Civil Procedure 4 (FRCP 4) in federal courts and by corresponding state rules of civil procedure in state courts. FRCP 4(l) specifically requires that proof of service be filed with the court, and most states have equivalent requirements. Without proper proof of service, the court cannot exercise personal jurisdiction over the defendant, and any judgment entered may be void and unenforceable.

The Affidavit of Service is executed by the person who performed the service (the process server, sheriff, or other authorized person) -- not by the party who requested service. The server attests under oath to the facts of the delivery: what documents were served, how they were served, when and where service occurred, and the identity of the person who received the documents. False statements in an Affidavit of Service constitute perjury and can result in sanctions, dismissal of the case, or criminal prosecution.

An Affidavit of Service is required every time legal documents are served on a party in a civil lawsuit. When a plaintiff files a complaint and summons, the defendant must be served in compliance with FRCP 4 (or the applicable state rule), and proof of service must be filed with the court within 90 days of filing the complaint (under FRCP 4(m)) or the case may be dismissed.

This document is needed when serving motions, discovery requests, subpoenas, and other pleadings during active litigation. While the initial service of process has the most stringent requirements (often requiring personal delivery), subsequent filings may be served by mail, email, or electronic filing systems, with corresponding affidavits of service.

Divorce proceedings, eviction actions, foreclosure notices, and restraining order petitions all require proof of service. In family law cases, proper service is especially critical because the court's jurisdiction over custody, support, and property matters depends on the respondent receiving notice.

Debt collection actions under the Fair Debt Collection Practices Act (FDCPA, 15 U.S.C. 1692) require proof that the debtor was properly served. Sewer service (falsely claiming service was made) is a serious problem in the debt collection industry and constitutes fraud.

Without a properly executed Affidavit of Service, the court cannot confirm that the opposing party received notice. This can result in delayed proceedings, denied default judgments, or reversal of judgments on appeal due to lack of proper service.

The identity of the person who performed service (the server) must be clearly stated, including their full name, address, and qualifications. In many states, process servers must be registered, licensed, or appointed by the court. The server must be at least 18 years old and not a party to the action (FRCP 4(c)(2)).

The documents served must be specifically identified by title, case number, and court. For example: 'Summons and Complaint in the matter of Smith v. Jones, Case No. 2024-CV-12345, filed in the Superior Court of California, County of Los Angeles.' Vague descriptions like 'legal papers' are insufficient and may be rejected by the court.

The method of service must be specified: personal service (hand-delivered directly to the named party), substituted service (left with a responsible adult at the person's usual place of abode), service by mail (sent via certified or first-class mail), or service by publication (published in a newspaper of general circulation when the party cannot be located). Each method has specific legal requirements under the applicable rules.

The exact date, time, and location of service must be recorded. For personal service, a physical description of the person served (approximate age, height, weight, race, and gender) helps confirm that the correct person received the documents. For substituted service, the name and relationship of the person who accepted the documents must be stated.

The affidavit must be signed by the server under penalty of perjury and, in most jurisdictions, notarized. The document must be filed with the court within the timeframe specified by the applicable rules -- typically within a specified number of days after service is completed. Some courts have specific forms for proof of service that must be used in lieu of a general affidavit.