An Acknowledgment of Service form is a short document you sign to confirm you received the papers starting a lawsuit against you. To complete it, fill in the case number, court name, party names, and the date you got the papers, then sign and date it. Return it to the plaintiff (or file it with the court, depending on the rules that apply), and then calendar the separate deadline for filing your actual answer.
What the Form Confirms
Signing this form, sometimes called a waiver of service, only proves the defendant knows about the lawsuit. It admits nothing about whether the claims have merit. You keep every right to fight the case, challenge jurisdiction, or raise any other defense.
Here is where people get into trouble: acknowledging service is not the same as filing an answer. The signed form tells the court the papers reached you. It does not respond to the complaint. You still owe the court a formal answer or motion within a separate deadline, and treating the acknowledgment as your one and only obligation is a fast path to a default judgment.
Information You Need to Fill In
Whether you’re working with the federal waiver form or a state version, the fields are essentially the same:
- Case number, printed on the summons or complaint, usually near the top of the first page. Every document filed in the case needs this number.
- Court name, in full, including the district or county.
- Party names, exactly as they appear on the complaint.
- The date you received the papers. This date anchors every deadline that follows, so record it accurately.
- Your signature.
An individual signs personally. If the papers are directed to a business or other entity, the signer must be someone authorized to accept service for that organization, such as an officer, registered agent, or managing partner. A signature from someone without that authority is not valid service and creates problems for both sides later.
The Federal Waiver Form Under Rule 4(d)
In federal court, the process is built into Rule 4(d) of the Federal Rules of Civil Procedure. Rather than pay a process server, the plaintiff mails you a copy of the complaint, two copies of official Form AO 399, and a prepaid return envelope. You fill out the waiver and mail it back.1Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
The form itself is one page and is available on the U.S. Courts website.2United States Courts. Waiver of the Service of Summons You confirm you received the complaint, acknowledge the lawsuit, agree to waive formal service, and note the date the request was sent to you. That send date matters because your answer deadline runs from it.
Why Signing Helps You
Rule 4(d) gives defendants a real reason to cooperate. Sign the waiver and your deadline to file an answer extends to 60 days from the date the request was sent, compared with 21 days after formal service. Defendants outside the United States get 90 days.1Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons The rule also says explicitly that signing the waiver does not give up your right to challenge personal jurisdiction or venue. You lose nothing on the merits by cooperating.
What Refusing Costs
If you’re in the United States and refuse to sign the waiver without good cause, the court must order you to pay the plaintiff’s costs of arranging formal service, including process server fees and the attorney’s fees spent on a motion to recover those costs.1Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons Believing the lawsuit is frivolous or that the court lacks jurisdiction is not good cause. The duty to avoid unnecessary service costs applies regardless of the merits.
How to Return or File the Completed Form
For the federal waiver, return it to the plaintiff using the prepaid envelope included with the request, or send it by any reliable method. The plaintiff files it with the court, and proof of service is complete. You don’t need to file anything with the court yourself at this stage.
State acknowledgment forms work differently. Many courts now allow or require electronic filing through a portal, where you upload the signed form as a PDF. Others accept hand-delivery to the clerk of court or filing by certified mail. Whichever method applies, keep a date-stamped copy or digital confirmation as proof that you met the deadline.
There is generally no separate filing fee for an acknowledgment of service or waiver form. Fees come later, when you file your answer or other responsive pleading.
Deadlines That Start Once You Sign
Returning the form starts a clock, and the clock is the whole point of the exercise. In federal court, a defendant who signs a waiver has 60 days from the date the waiver request was sent to file an answer to the complaint.1Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons A defendant who was formally served instead has 21 days after service to respond.3Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections: When and How Presented State deadlines vary, though 20 to 30 days after service is common.
If you need more time, ask before the deadline runs. Under Rule 6(b), a court may extend a deadline for good cause when the request is made before the original deadline expires. After the deadline passes, extensions are still possible but only for excusable neglect, a much harder standard.4Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time; Time for Motion Papers Opposing counsel will sometimes agree informally to a short extension, but get the agreement in writing and file a stipulation so the record reflects it.
What Happens If You Miss the Answer Deadline
If the deadline passes without an answer or other responsive pleading, the plaintiff can ask the clerk to enter your default under Rule 55. For claims seeking a specific dollar amount, the clerk can enter a default judgment on the spot, with no hearing and no further notice to you, as long as the plaintiff provides an affidavit showing what’s owed.5Legal Information Institute. Federal Rules of Civil Procedure Rule 55 – Default; Default Judgment For more complex claims, the court holds a hearing on damages, but by then you’ve lost the right to contest liability. Not showing up is treated as conceding every allegation in the complaint.
Mistakes That Cause Real Damage
The costliest error is treating the acknowledgment as your entire response. Signing only confirms you got the papers. You still owe a separate answer or motion within the applicable deadline, or the plaintiff can seek a default judgment.
Another common problem is recording the wrong date. Your deadline runs from the date you were served or, for the federal waiver, the date the request was sent to you. It does not run from the date the complaint was filed with the court. Being off by even a few days can mean a late response you didn’t know was late.
Ignoring a waiver request is the worst option available. The plaintiff arranges formal service anyway, your answer window drops from 60 days back to 21, and the court orders you to reimburse the plaintiff’s service costs. There is no strategic upside to letting the request sit.