FINRA Rule 9131

FINRA Rule 9131 establishes three requirements for complaint service: who is responsible for serving it, how it must be served, and what filing obligations attach to service. 

The rule provides that the Department of Enforcement is responsible for serving the complaint on each party, that service is accomplished through the methods prescribed in FINRA Rule 9134, that service may be made on counsel when counsel agrees to accept it, and that the complaint together with its certificate of service must be filed with FINRA pursuant to FINRA Rule 9135.

FINRA Rule 9131 sits within the 9130 Service; Filing of Papers subsection of the 9100 Application and Purpose section of the 9000 Code of Procedure series. 

It was amended effective October 18, 1990 in the predecessor NASD framework, amended by SR-NASD-97-28 effective August 7, 1997, amended by SR-NASD-99-76 effective September 11, 2000, amended by SR-FINRA-2008-021 effective December 15, 2008 as part of the FINRA rulebook consolidation announced in Regulatory Notice 08-57, amended by SR-FINRA-2011-044 effective March 30, 2012 as announced in Regulatory Notice 12-12 to add the counsel acceptance of service provision, amended by SR-FINRA-2018-027 effective August 3, 2018 to reflect FINRA's internal reorganization of enforcement operations by removing the Department of Market Regulation as a co-equal serving authority and consolidating complaint service responsibility exclusively in the Department of Enforcement, and most recently amended by SR-FINRA-2025-013 effective October 7, 2025.

FINRA Rule 9131(a): Service Responsibility and the Counsel Acceptance Provision

FINRA Rule 9131(a) establishes two operative provisions. The default rule is that a complaint shall be served on each party by the Department of Enforcement — the singular institutional actor responsible for initiating and prosecuting FINRA disciplinary proceedings. The 2018 amendment through SR-FINRA-2018-027 made this exclusivity explicit by removing the Department of Market Regulation as an alternative serving authority, reflecting FINRA's internal reorganization that consolidated enforcement functions under a single Department of Enforcement. Prior to August 2018, FINRA Rule 9131(a) allowed either the Department of Enforcement or the Department of Market Regulation to serve complaints, corresponding to a historical structure in which market regulation enforcement and member regulation enforcement were conducted by separate FINRA departments. The consolidation of serving authority in the Department of Enforcement alone reflects the organizational reality of modern FINRA enforcement.

The counsel acceptance provision — added by SR-FINRA-2011-044 effective March 30, 2012 — creates an important efficiency mechanism: when counsel for a party or another person authorized to represent others under FINRA Rule 9141 agrees to accept service of the complaint, the Department of Enforcement may serve the complaint on counsel rather than directly on the respondent. 

This provision recognizes the practical reality of represented respondents — in many cases, a respondent who is already represented by counsel in connection with a FINRA investigation has counsel available to accept service of the formal complaint that follows, and serving counsel directly is more efficient and equally effective than serving the respondent through the standard methods. 

The agreement to accept service must be affirmative — the provision does not permit the Department of Enforcement to deem counsel served absent an express agreement. Service on counsel as provided in FINRA Rule 9131(a) is accomplished pursuant to FINRA Rule 9134(a), which provides for personal service, service by mail and service by courier; personal service in the counsel context can mean leaving a copy at counsel's office with an employee or other person in charge.

The 2012 amendment also resolved an ambiguity in the prior rule regarding who serves documents other than complaints that initiate proceedings — such as notices initiating expedited proceedings under the Rule 9550 series or notices initiating statutory disqualification proceedings under the Rule 9520 series. The current rule provides that documents initiating a proceeding — which encompasses both complaints and other initiating documents — shall be served pursuant to FINRA Rule 9134, and that service on counsel is available when counsel agrees to accept it.

FINRA Rule 9131(b): How the Complaint Is Served

FINRA Rule 9131(b) provides the operational direction for the mechanics of complaint service: a complaint or document initiating a proceeding shall be served pursuant to FINRA Rule 9134. This cross-reference to FINRA Rule 9134 — the master service methods rule — is the mechanism through which the specific permissible methods of service for complaints are defined.

FINRA Rule 9134 provides three traditional service methods under FINRA Rule 9134(a) — personal service, service by mail and service by courier — with the address and completion procedures under FINRA Rule 9134(b), and service through the OHO Portal under FINRA Rule 9134(c). For complaints specifically, FINRA Rule 9134 makes clear that OHO Portal service — while available for other documents in OHO proceedings — is not the designated method for complaint service, which continues to be accomplished by personal service or mail and courier. This distinction reflects a deliberate policy judgment about the reliability of service for the most consequential document in any proceeding.

Personal service of a complaint on a respondent who is a natural person is accomplished by delivering a copy directly to the person. Personal service on a member firm is accomplished by delivering a copy to an officer, partner, managing or general agent, or contact employee as set forth on Form BD, or to any other agent authorized to accept service on behalf of the firm, at the firm's business address as reflected in the Central Registration Depository. 

Service of a complaint by mail requires mailing a copy through the U.S. Postal Service by first class certified mail or Express Mail, addressed to the respondent at the residential address reflected in the Central Registration Depository or at another address FINRA Rule 9134(b) permits. Service by courier requires sending a copy through a courier service that generates a written confirmation of receipt or of attempts at delivery, addressed in the same way.

The critical operational question of what address must be used for complaint service connects directly to FINRA Rule 8210(d)'s CRD address deemed receipt standard for investigative notices — the last known address of record in the Central Registration Depository is the governing standard for both FINRA Rule 8210 information requests and FINRA Rule 9131 complaint service. 

A respondent who has failed to maintain a current CRD address has not thereby escaped service — where the serving party has no actual knowledge that the address is out of date, service at the CRD address is complete regardless of whether the respondent actually receives the document, as the respondent's obligation to maintain a current CRD address is itself a regulatory requirement under FINRA Rule 4517.

Service by mail is complete upon mailing. When service is made by first class, certified, or registered mail, FINRA Rule 9138's time computation rules provide that three additional days are added to the prescribed period for response — recognizing that mailed service takes time to arrive and that requiring a response within the same period as personal service would be unfair when the respondent receives the document days after it was deposited in the mail.

FINRA Rule 9131(c): The Simultaneous Filing Requirement

FINRA Rule 9131(c) imposes a critical filing obligation that accompanies complaint service: a complaint served on a respondent, and each document initiating a proceeding served on a party, together with the certificate of service executed in connection with that service, must be filed with FINRA pursuant to FINRA Rule 9135, and FINRA Rule 9212(a)(1) requires a disciplinary complaint to be filed with OHO at the time of service. 

The phrase at the time of service comes from FINRA Rule 9212(a)(1): filing accompanies service rather than following it, and in proceedings before OHO a complaint is deemed filed as of the date it is submitted to the OHO Portal under FINRA Rule 9135.

This simultaneity requirement serves two essential functions. First, it ensures that the Office of Hearing Officers' case file is complete and current from the very beginning of the proceeding — the moment the complaint is served on the respondent, OHO has a complete copy for the official record. 

Second, it creates the evidentiary record of service through the required certificate of service — a document that identifies the person or persons served, the method of service, the date of service, and, if service is not made in person, the address at which service was made, and that is executed by the person who made the service. 

The certificate of service is the legal documentation that establishes when the proceeding formally began and from which all subsequent deadlines are computed.

The filing obligation under FINRA Rule 9131(c) is directed to FINRA Rule 9135 — the filing of papers with the Adjudicator rule — which in the OHO proceeding context means filing through the OHO Portal as the primary electronic filing mechanism for OHO proceedings following the October 2025 modernization. 

The filing requirement ensures that OHO — as the institutional administrator of the disciplinary proceeding — has the complaint and service documentation in its system at the moment the proceeding commences, enabling OHO to promptly assign a Hearing Officer, issue the initial scheduling order, and notify all parties of the proceeding's commencement.

The Complaint as the Foundation of FINRA Rule 9131's Significance

The importance of FINRA Rule 9131's service requirements cannot be understood in isolation from the nature of the complaint itself. FINRA Rule 9212 — Complaint Issuance: Requirements, Service, Amendment, Withdrawal, and Docketing — establishes what a complaint must contain: a written document signed by the Department of Enforcement, specifying in reasonable detail the conduct alleged to constitute the violative activity and identifying each rule, regulation, or statutory provision the respondent is alleged to have violated, with each cause of action stated separately if the complaint contains multiple charges. 

Complaints are served by the Department of Enforcement on each party pursuant to FINRA Rule 9131 and paragraphs (a) and (b) of FINRA Rule 9134, and filed at the time of service with OHO pursuant to FINRA Rules 9135, 9136, and 9137.

Proper service of the complaint is the jurisdictional act that brings the respondent formally within the Code of Procedure's framework. A respondent who has not been properly served has not been properly brought into the proceeding — any subsequent orders, decisions, or sanctions issued without proper complaint service would be procedurally vulnerable. 

The 2012 amendment's clarification that counsel acceptance of service must be affirmative — not assumed — reflects this jurisdictional significance: FINRA must be able to demonstrate that the respondent was properly brought into the proceeding through a documented act of service that the respondent or their counsel actually received.

The Twenty-Five Day Answer Period

The operational consequence of complaint service that practitioners most immediately encounter is the triggering of the respondent's obligation to file an answer. FINRA Rule 9215 — Answer to Complaint — requires each respondent named in a complaint to serve an answer on all other parties within twenty-five days after service of the complaint on that respondent, and to simultaneously file the answer with OHO. The twenty-five day period begins running from the date of service as established by FINRA Rule 9131 and computed pursuant to FINRA Rule 9138 — with the three-day mail service addition applying when service was accomplished by mail under FINRA Rule 9134(b). A respondent who fails to file an answer within the required period faces the default consequences of FINRA Rule 9269 — a default decision that may be entered against them on the basis of the complaint's allegations.

Connection to FINRA Rules 8210 and 4517

FINRA Rule 9131's service framework connects directly to FINRA Rule 8210's investigative notice provisions — both rules use the CRD address as the governing standard for deemed receipt of regulatory documents. A respondent who maintains a current CRD address as required by FINRA Rule 4517 — Update to Registration Information — is reachable through both FINRA Rule 8210 investigative notices and FINRA Rule 9131 complaint service. A respondent who has allowed their CRD address to lapse has failed to fulfill a separate regulatory obligation and cannot use that failure to escape proper service. The connection reinforces the importance of current CRD address maintenance as a foundational compliance obligation that enables FINRA's entire regulatory and enforcement framework to function.

Serving Every Respondent Named in the Complaint

FINRA Rule 9131(a) requires that a complaint be served on each Party by the Department of Enforcement. The requirement runs party by party. A single complaint often names a member firm and one or more of its associated persons together. In that case each respondent is a separate Party who must be served in their own right. Serving the firm does not serve the individuals the complaint also names, and serving one individual does not serve a co-respondent.

Consider a complaint naming Harbor Point Securities and two of its registered representatives, Ms. Lane and Mr. Ortiz. Enforcement can serve the firm under FINRA Rule 9134(b)(2) by serving an officer or other person that rule names, at the firm's business address as reflected in the Central Registration Depository. That act serves Harbor Point and nobody else. Ms. Lane and Mr. Ortiz must each be served by one of the methods and at one of the addresses that FINRA Rule 9134 permits for a natural person. This holds even if both work at the same office where the firm's officer was served.

Because service is made on each respondent separately, co-respondents need not be served in the same way. FINRA Rule 9131(b) allows each of them to be served by any method in paragraphs (a) and (b) of FINRA Rule 9134. Enforcement might serve the firm by courier and hand the complaint to Ms. Lane personally. When the methods differ, the certificate of service filed with FINRA must say why a different method was used for one Party.

Service on Counsel in Practice

FINRA Rule 9131(a) opens with "Except as provided below". The exception that follows is the counsel route. When counsel for a Party, or another person authorized to represent others under FINRA Rule 9141, agrees to accept service of the complaint, the Department of Enforcement may serve the complaint on that counsel or representative. Service made this way takes the place of serving the Party directly. It is the exception to the default of serving the respondent.

The agreement belongs to the counsel of a particular Party, so it reaches only that Party. Suppose the same law firm represents Harbor Point and has agreed to accept service of the complaint on the firm's behalf, but has made no such agreement for Mr. Ortiz, who is represented separately. Enforcement may serve Harbor Point's complaint on the law firm. It must still serve Mr. Ortiz himself, or his own counsel if that counsel agrees to accept service. Counsel who represents two respondents and agrees to accept service for both may be served for both.

The agreement must be an agreement to accept service of the complaint. Counsel may have received FINRA's investigative correspondence on the client's behalf during the investigation. That practice is not the agreement FINRA Rule 9131(a) describes. Before serving a complaint on counsel, Enforcement needs counsel's agreement to accept service of that complaint.

Service on counsel who has agreed is made "as specified in Rule 9134(a)". FINRA Rule 9134(a) sets out three methods: personal service, service by mail through the U.S. Postal Service, and service by courier. Any of them may be used to reach counsel, for example by leaving the complaint at counsel's office with the employee or other person in charge, or by sending it through a courier service that generates written confirmation of receipt. Electronic mail is not among the methods in FINRA Rule 9134(a), and neither is submission to the OHO Portal. A complaint e-mailed to counsel has therefore not been served on counsel under FINRA Rule 9131(a), even if counsel has agreed to accept service.

When the complaint goes to counsel, it is delivered at counsel's office or address, because counsel is the person served. The respondent's own address in the Central Registration Depository plays no part in that act of service. For a respondent whose recorded address is out of date, counsel's agreement to accept service therefore gives Enforcement a way to serve without relying on that address.

Service on counsel is complete when FINRA Rule 9134(b)(3) says it is: on delivery for personal and courier service, and on mailing for service by mail. When counsel later passes the complaint to the client does not change the date on which service was complete.

Worked Scenario: A Registered Representative Who Has Left the Firm

A separate complaint names Mr. Dale, who resigned from his member firm before the complaint issued and has not retained counsel. FINRA Rule 9131(b) sends Enforcement to paragraphs (a) and (b) of FINRA Rule 9134. Under paragraph (b)(1), papers may be served on a natural person at the residential address reflected in the Central Registration Depository. If Enforcement mails the complaint, FINRA Rule 9134(a)(2) requires U.S. Postal Service first class certified mail or Express Mail for a complaint served on a Respondent.

Now suppose Mr. Dale has joined another member firm, Crestline Capital. FINRA Rule 9134(b)(1) also permits service at the business address, as reflected in the Central Registration Depository, of the entity with which the natural person is employed or affiliated. It also permits service at a business address, such as a branch office, where he is employed or physically present during a normal business day. Crestline's recorded business address, or the branch where he now works, is therefore available to Enforcement as well as his residential address.

The position changes if Enforcement actually knows that Mr. Dale's residential address in the Central Registration Depository is out of date, for instance because mail sent there earlier came back. FINRA Rule 9134(b)(1) then requires duplicate copies to be served at his last known residential address and at the business address in the Central Registration Depository of the entity with which he is employed or affiliated. Service at the recorded address alone is the case the current article describes when it treats service at the CRD address as complete whether or not it is received. That treatment assumes Enforcement has no such knowledge.

The Filing Packet: Complaint and Certificate Together

FINRA Rule 9131(c) requires that a complaint served on a Respondent be filed with FINRA pursuant to FINRA Rule 9135, "along with the certificate of service executed in connection with the service upon such Respondent". A complaint filed without its certificate does not satisfy the requirement, because the filing is of the two documents together.

The certificate that accompanies the filing is tied to service on a particular Respondent. Suppose Harbor Point is served on a Monday and Ms. Lane, who was travelling, is served on the Thursday. The certificate executed for each of those acts of service is filed with FINRA, so that the record shows each respondent's service.

FINRA Rule 9135(c) says what the certificate states: the name of the person or persons served, the date on which service is made, the method of service, and, if service is not made in person, the address to which service is made. It is executed by the person who made the service. If Enforcement uses a process server to hand the complaint to Ms. Lane, the certificate for that service is executed by the process server who made it.

The filing requirement is not limited to complaints. FINRA Rule 9131(c) applies equally to "each document initiating a proceeding that is served upon a Party". Such a document, together with the certificate of service executed for its service, is filed with FINRA pursuant to FINRA Rule 9135 in the same way as a complaint.

Common Errors in Complaint Service

The errors that FINRA Rule 9131 and the rules it incorporates expose fall into a few recurring patterns. One is treating service on a member firm as service on the associated persons named alongside it. Each Party must be served, so a firm officer's receipt of the complaint does not bring an individual respondent into the proceeding.

A second is extending one respondent's counsel arrangement to another. Counsel's agreement to accept service of the complaint is the agreement of counsel for a Party. Serving a co-respondent through counsel who has not agreed to accept service for that co-respondent is not service under FINRA Rule 9131(a).

A third is choosing a method the rule does not reach. Service on counsel who has agreed is made as specified in FINRA Rule 9134(a), which lists personal service, mail and courier. A complaint sent to a respondent by mail must go by U.S. Postal Service first class certified mail or Express Mail.

A fourth is filing the complaint without its certificate, or filing a certificate that covers some respondents and not others. FINRA Rule 9131(c) ties the filing to the certificate executed in connection with service upon each Respondent. The existing section on the consequences of defective service explains why an incomplete record of service matters: a respondent who has not been properly served has not been properly brought into the proceeding.

Serving the Complaint Through the Methods of FINRA Rule 9134

FINRA Rule 9131(b) does not describe any method of service itself. It directs that a complaint be served pursuant to paragraphs (a) and (b) of FINRA Rule 9134, so every practical question about how a complaint reaches a respondent is answered by applying that rule to the complaint. The scenarios in this section show how that works for the serving Department and for the respondent.

Suppose an Enforcement paralegal sends a complaint to a respondent in an ordinary first class envelope because that is how the office's routine correspondence goes out. Ordinary first class mail is one of the classes FINRA Rule 9134(a)(2) allows for papers generally. The same paragraph then provides that a complaint "shall be served upon a Respondent by U.S. Postal Service first class certified mail or Express Mail". The envelope has not served the complaint, and it must go again by one of those two classes or by another permitted method.

Personal service under FINRA Rule 9134(a)(1) can be made at the respondent's home, but only by leaving the copy with "a person of suitable age and discretion then residing therein". Suppose a process server finds the respondent out and hands the complaint to the respondent's adult cousin, who is staying for the weekend but lives elsewhere. That hand-over does not meet the text, because the cousin does not reside at the dwelling.

Courier service counts only where the courier service "generates a written confirmation of receipt or of attempts at delivery". Suppose Enforcement uses a local messenger that leaves packages at the door and issues no confirmation of any kind. That delivery is not service by courier within FINRA Rule 9134(a)(3), whatever the messenger later says about where the package was left.

For a member firm, the address rules work in the same way as for individuals. Papers served on an entity are served at its business address as reflected in the Central Registration Depository. Suppose Enforcement knows that a firm has moved and has not updated that address. FINRA Rule 9134(b)(2) then requires duplicate copies to be served at the firm's last known address.

The Hearing Officer has a limited power to relieve a serving party of the Central Registration Depository addresses. FINRA Rule 9134(b)(1) allows the Hearing Officer to "waive the requirement of serving documents (other than complaints) at the addresses listed in the Central Registration Depository" where those addresses are shown to be invalid and a more current address is available. Because the complaint is carved out of that power, Enforcement cannot ask the Hearing Officer to let it serve the complaint only at a newer address instead of the recorded ones.

From Service to Answer: Counting the Time

Service under FINRA Rule 9131 starts the respondent's time to answer. FINRA Rule 9215(a) requires each Respondent named in a complaint to serve an answer on all other Parties "within 25 days after service of the complaint on such Respondent". Because the period runs from service on each Respondent, co-respondents served on different days have different deadlines. Suppose Harbor Point is served personally and Ms. Lane is served personally seven days later. Ms. Lane's answer period ends seven days after Harbor Point's.

FINRA Rule 9138 supplies the arithmetic. A "day" is a calendar day, and the day of the act from which the period runs is not counted. Suppose a complaint is handed to a respondent on the 2nd of a month. The count starts on the 3rd, and the twenty-fifth day is the 27th. Saturdays, Sundays and Federal holidays inside the period are counted, because the rule excludes intermediate weekend days and holidays only when the prescribed period is ten days or less.

The last day is treated differently. If the last day of the period is a Saturday, Sunday or Federal holiday, the period "runs until the end of the next day that is not a Saturday, Sunday, or Federal holiday". Suppose the twenty-fifth day is a Monday that is a Federal holiday. The answer is then due by the end of the Tuesday.

The method of service can change the count. FINRA Rule 9138(c) adds three days to the prescribed period for response "if service is made by U.S. Postal Service first class, certified, or registered mail". Service by courier is complete upon delivery under FINRA Rule 9134(b)(3). A respondent served by courier therefore has twenty-five days counted from the day of delivery, with no postal addition.

The Hearing Officer assigned to the proceeding may extend the answer period for good cause. A respondent who needs more time therefore asks the Hearing Officer, rather than treating the period as flexible.

When No Answer Arrives

FINRA Rule 9215(f) sets out what follows if a Respondent "does not file an answer or make any other filing or request related to the complaint" with the Office of Hearing Officers within the time required. In that case the Department of Enforcement sends a second notice requiring an answer within 14 days after service of that notice. The notice states that failure to reply may allow the Hearing Officer to treat the complaint's allegations as admitted and to issue a default decision under FINRA Rule 9269.

The second notice travels the way the complaint did. In proceedings before the Office of Hearing Officers, the OHO Portal is the required method for most papers. However, FINRA Rule 9134(c)(1)(B) provides that "service of papers in cases of default under Rule 9215(f) and Rule 9269(a) shall be served pursuant to paragraphs (a) and (b) of this Rule". A second notice to a respondent who has not answered is therefore served by personal service, mail or courier at the addresses those paragraphs prescribe. Uploading it to the Portal is not enough.

The trigger for the second notice is silence of a particular kind. Suppose a respondent files nothing with the Office of Hearing Officers but, within the answer period, files a request related to the complaint, such as a request for more time. That respondent is not in the position FINRA Rule 9215(f) describes, because the paragraph applies to a Respondent who has made no answer and no other filing or request related to the complaint.

How FINRA Rule 9131 Hands Off to the Rest of the Proceeding

Complaint service is the one point in an Office of Hearing Officers proceeding where the traditional methods are required. After it, the service rules change. FINRA Rule 9215(a) requires the answer to be served "Pursuant to Rule 9133", and FINRA Rule 9133(b) provides that in proceedings before the Office of Hearing Officers the Parties serve documents pursuant to Rule 9134(c), that is, through the OHO Portal. A respondent who received the complaint by certified mail still serves the answer through the Portal.

Representation also works differently once the complaint has been served. The complaint reaches counsel only where counsel agrees to accept it under FINRA Rule 9131(a). For later papers, FINRA Rule 9133(d) provides that whenever service is required on a person represented by counsel or a representative "who has filed a notice of appearance pursuant to Rule 9141, service shall be made upon counsel or the representative". Suppose a respondent is served personally and then retains counsel, who files a notice of appearance. Enforcement's later motions are served on that counsel, even though counsel never agreed to accept anything.

Filing the complaint under FINRA Rule 9131(c) also brings in a requirement about the filer's own contact details. FINRA Rule 9135(d) provides that "at the first occurrence of a Party filing a Complaint, Answer, or other paper, the Party must include a mailing address and electronic mail address" at which communications may be sent. For the Department of Enforcement, that first occurrence is the filing of the complaint. For a respondent, it is ordinarily the answer. Each Party must serve any change of those addresses on all other Parties and file it with the Adjudicator.

Examination Relevance and Key Takeaways

FINRA Rule 9131 is tested on the Series 24 General Securities Principal examination in the context of the Code of Procedure, complaint initiation, and the procedural rights and obligations that attach when a FINRA disciplinary complaint is served. The rule's connection to FINRA Rule 9212's complaint content requirements, FINRA Rule 9134's service methods, FINRA Rule 9215's answer obligation, and FINRA Rule 9138's time computation makes it a central rule in any examination question tracing the procedural lifecycle of a FINRA disciplinary proceeding from complaint issuance through answer.

The key points to retain are these: FINRA Rule 9131 requires that complaints be served on each party by the Department of Enforcement — the sole serving authority following the August 2018 internal reorganization amendment through SR-FINRA-2018-027; when counsel for a party or a person authorized to represent others under FINRA Rule 9141 agrees to accept service, the Department of Enforcement may serve the complaint on counsel pursuant to FINRA Rule 9134(a) — a provision added by SR-FINRA-2011-044 effective March 30, 2012; complaints and documents initiating proceedings are served pursuant to FINRA Rule 9134 — specifically by personal service or mail and courier, not by OHO Portal or email which are reserved for subsequent inter-party documents; service by mail is complete upon mailing, and service by first class, certified, or registered mail adds three days to the prescribed period for response under FINRA Rule 9138; the complaint together with its certificate of service must be filed with FINRA pursuant to FINRA Rule 9135, at the time of service as FINRA Rule 9212(a)(1) requires — creating a complete OHO file from the moment the proceeding begins; the certificate of service documents the persons served and the method, date, and (if service is not made in person) address of service and is the foundational evidentiary record establishing when all subsequent deadlines begin running; proper complaint service triggers the respondent's twenty-five day obligation to file an answer under FINRA Rule 9215; failure to answer within the required period exposes the respondent to a default decision under FINRA Rule 9269; the CRD address is the governing standard for complaint service addresses, connecting FINRA Rule 9131 to FINRA Rule 4517's address maintenance obligation and FINRA Rule 8210(d)'s deemed receipt framework; and the rule was amended by SR-FINRA-2018-027 effective August 3, 2018 consolidating service authority in the Department of Enforcement alone, and most recently by SR-FINRA-2025-013 effective October 7, 2025.