CPLR 2103 is the New York rule that controls how the papers exchanged during a civil lawsuit — motions, discovery demands, notices, oppositions, and the rest — move between the parties after the case is already underway. It tells you who may serve those papers, who must receive them, which seven delivery methods are valid, when each one counts as complete, and how many extra days the method adds to the recipient’s response deadline. It does not govern the initial summons and complaint; that is a separate problem under a separate rule.
Who Can Serve and Who Must Be Served
Any person at least eighteen years old who is not a party to the action can serve interlocutory papers.1New York State Senate. New York Civil Practice Law and Rules R2103 The non-party requirement is strict. A plaintiff cannot personally mail interrogatories to the defendant; a defendant cannot hand opposition papers to the plaintiff’s lawyer. The task usually falls to a paralegal, legal assistant, colleague, or professional process server.
Once an attorney has appeared for a party, every subsequent paper has to go to the attorney, not the party. Serving the represented party directly can be treated as defective. If the party is self-represented, or if their attorney cannot be located or served, service goes directly to the individual using one of the methods below.1New York State Senate. New York Civil Practice Law and Rules R2103 A court may order a different arrangement when circumstances call for it.
The Seven Methods of Service
CPLR 2103(b) lists seven ways to get the papers to opposing counsel or a self-represented party. Each has its own completion rule, and some have preparation steps that are easy to miss.
Personal Delivery to the Attorney
Handing the papers directly to the attorney is always valid under paragraph (b)(1).1New York State Senate. New York Civil Practice Law and Rules R2103
Delivery at the Attorney’s Office
Paragraph (b)(3) covers the office. If the office is open, leave the papers with the person in charge; if nobody is in charge but the office is open, leave them in a conspicuous place; if the office is closed, deposit them in the office letter drop or mailbox in a sealed wrapper addressed to the attorney.1New York State Senate. New York Civil Practice Law and Rules R2103 The open/closed distinction is what controls which option you use.
Delivery at the Attorney’s Residence
Paragraph (b)(4) allows leaving the papers at the attorney’s home with a person of suitable age and discretion, but only when service at the office cannot be made.1New York State Senate. New York Civil Practice Law and Rules R2103 It is a fallback, not an option you choose for convenience.
Under paragraph (b)(2), mail the papers in a first-class, postage-paid envelope to the address the attorney has designated for service, or to the attorney’s last known address if none has been designated. Service is complete the moment you drop the envelope in a post office or official USPS depository.1New York State Senate. New York Civil Practice Law and Rules R2103 What matters is the mailing date, not the delivery date, and you do not need proof the other side received it.
Overnight Delivery
Paragraph (b)(6) permits service by any delivery service that regularly accepts items for overnight delivery to any address in the state — FedEx and UPS are the common ones.2New York State Senate. New York CVP Section 2103 Service is complete when you deposit the properly addressed package with the courier before its cutoff time for overnight delivery. Miss the cutoff and your service date moves to the next day.
Facsimile
Paragraph (b)(5) allows fax service only when the receiving attorney has designated a fax number for that purpose. Listing a fax number in the address block on any paper filed or served in the case counts as consent, and consent can later be withdrawn by serving notice on the other parties.1New York State Senate. New York Civil Practice Law and Rules R2103
Fax service is not complete just because the transmission went through. You also have to mail a hard copy to the attorney.1New York State Senate. New York Civil Practice Law and Rules R2103 Skip the follow-up mailing and the service is incomplete, no matter how clean the confirmation sheet looks.
Electronic Means
Paragraph (b)(7) covers electronic service, including through the New York State Courts Electronic Filing system (NYSCEF). Electronic service is allowed where authorized by rules of the Chief Administrator of the Courts, and the party’s written consent is required unless the rules say otherwise.2New York State Senate. New York CVP Section 2103 Every electronic transmission must include a subject line indicating it relates to a court proceeding.
Where NYSCEF e-filing is mandatory, all parties file and serve through the system regardless of individual consent.3New York State Unified Court System. NYSCEF – Frequently Asked Questions In consensual e-filing cases, each attorney who wants to participate registers consent in NYSCEF for that specific case.4New York State Unified Court System. 22 NYCRR 202.5-b – Electronic Filing in Supreme Court; Consensual Program A party’s refusal to consent does not prevent the others from e-filing among themselves.
Extra Days the Recipient Gets
Because mail and overnight packages take time to arrive, CPLR 2103 adds days to the recipient’s response period whenever a legally prescribed deadline runs from the date of service. The extensions are automatic. The amount depends on the method and, for mail, on where the envelope was sent from:
- Mail from within New York: five extra days.1New York State Senate. New York Civil Practice Law and Rules R2103
- Mail from outside New York but within the United States: six extra days.1New York State Senate. New York Civil Practice Law and Rules R2103
- Overnight delivery: one extra business day.1New York State Senate. New York Civil Practice Law and Rules R2103
That one-day gap between in-state and out-of-state mail is worth watching. If a New York attorney mails motion papers from a satellite office in New Jersey, opposing counsel gets six days, not five. Personal delivery, office delivery, and electronic service through NYSCEF carry no automatic extension; the clock starts on the service date.
How the Extensions Stack on Motion Deadlines
The mailing extension works directly with CPLR 2214, which sets motion notice periods. A notice of motion and supporting papers must be served at least eight days before the return date. If the motion demands it and is served at least sixteen days before the return date, answering papers are due at least seven days before that date.5FindLaw. New York Civil Practice Law and Rules CVP Rule 2214
When you mail those papers instead of personally delivering them, you add the CPLR 2103 extension to the CPLR 2214 notice period. A notice of motion mailed from within New York that ordinarily requires eight days’ notice has to be mailed at least thirteen days before the return date — eight plus five. Use overnight delivery and the minimum becomes nine days (eight plus one business day). Mail from out of state and it is fourteen. Miscounting here is one of the most common ways motion papers get rejected as untimely.
When the Last Day Falls on a Weekend or Holiday
New York’s General Construction Law section 25-a extends any deadline that lands on a Saturday, Sunday, or public holiday to the next business day.6New York Public Law. New York General Construction Law Section 25-A If the five-day mailing extension pushes a response deadline onto a Sunday, you have until Monday.
Proving Service Happened
Correct service means little if you cannot prove it. Under CPLR 306, proof of service identifies the papers served, the person who received them, the date and time, the address or place of service, and the manner of service, and it shows that the person who made service was authorized to do so.7FindLaw. New York Civil Practice Law and Rules CVP Rule 306
A sheriff or other public officer files a certificate of service. Anyone else files an affidavit, sworn under penalty of perjury.7FindLaw. New York Civil Practice Law and Rules CVP Rule 306 For mail, a USPS Certificate of Mailing confirms the date you handed the envelope to the Postal Service, though it does not track delivery or capture a recipient signature.8USPS. Certificate of Mailing – The Basics For fax, keep the transmission confirmation report together with proof that you mailed the follow-up hard copy.
What Defective Service Costs You
When interlocutory service is defective, the court can disregard the paper. A motion served without adequate notice can be denied on procedural grounds before the judge reads the substance. Opposition papers served a day late can be rejected, leaving the motion unopposed. Arguments you lose this way are not easy to get back.
Filing a false affidavit of service carries its own exposure. Swearing you mailed something on a date you did not is perjury, and courts take the integrity of proof of service seriously; a pattern of unreliable affidavits can lead to sanctions and grievance referrals for the attorneys involved.
One boundary worth keeping in mind: CPLR 2103 does not govern service of the initial summons and complaint. Those are handled under separate rules, with separate consequences for failure, including dismissal under CPLR 306-b.9New York State Senate. New York Civil Practice Law and Rules CVP 306-b Everything in CPLR 2103 assumes the case is already open.