Rule 26 Expert Disclosures: Sample Forms, Report Contents, and Deadlines

A Rule 26 expert disclosure sample form has two versions, because Federal Rule of Civil Procedure 26(a)(2) treats retained experts and non-retained experts differently. For a retained expert, you serve a short notice that identifies the witness and attaches a signed written report covering six required categories. For a non-retained expert, such as a treating physician, you serve a notice that states the subject matter of the testimony and summarizes the facts and opinions the witness will offer. Both versions are illustrated below.¹

Which Form You Need: Retained or Non-Retained

The first question is which category your witness falls into, because it dictates the form.

The retained category covers experts specially employed to give testimony in the case, along with any party employee whose regular job duties involve expert testimony. These witnesses must produce a full written report, signed personally by the expert.¹

The non-retained category covers witnesses who acquired specialized knowledge through their involvement in the underlying events rather than through litigation. A treating physician is the classic example. No written report is required. Instead, the disclosure states the subject matter the witness will address and a summary of the facts and opinions expected.¹ A court can modify these requirements by order, and parties can also agree to different arrangements by stipulation.

Watch the boundary. If a treating physician will offer opinions about causation or future medical needs that go beyond the treatment actually provided, a court may decide the testimony crosses into retained-expert territory and require a full report. Match the disclosure to the scope of testimony you actually need.

Sample Disclosure Form for a Retained Expert

No official template exists, but the format is standardized across federal practice. The disclosure is served as a notice, with the expert’s signed report attached.

IN THE UNITED STATES DISTRICT COURT
FOR THE [DISTRICT NAME]

[Plaintiff Name], Plaintiff,
v.
[Defendant Name], Defendant.
Case No. [XX-XXXXX]

PLAINTIFF’S RULE 26(a)(2) EXPERT WITNESS DISCLOSURE

Pursuant to Federal Rule of Civil Procedure 26(a)(2), Plaintiff discloses the following retained expert witness:

Expert Witness: [Full Name], [Degree/Credentials]
Field of Expertise: [e.g., Biomechanical Engineering]
Employer/Affiliation: [Organization and Address]

[Expert Name] has been retained to provide expert testimony in this matter. In accordance with Rule 26(a)(2)(B), [Expert Name]’s signed written report is attached as Exhibit A. The report contains:

1. A complete statement of all opinions to be expressed and the basis and reasons for each opinion;
2. The facts and data considered in forming those opinions;
3. Exhibits to be used to summarize or support the opinions;
4. The witness’s qualifications, including publications from the previous ten years (curriculum vitae attached as Exhibit B);
5. A list of cases in which the witness testified as an expert at trial or by deposition during the previous four years (attached as Exhibit C); and
6. A statement of compensation to be paid for study and testimony in this case.

Plaintiff reserves the right to supplement this disclosure and to designate rebuttal experts following Defendant’s disclosure.

Dated: [Date]
[Attorney Name], [Bar Number]
[Firm Name]
[Address, Phone, Email]
Attorney for Plaintiff

Sample Disclosure Form for a Non-Retained Expert

Shorter, but still substantive. The summary must give the opposing party enough to prepare cross-examination.¹

PLAINTIFF’S RULE 26(a)(2)(C) EXPERT WITNESS DISCLOSURE

Pursuant to Federal Rule of Civil Procedure 26(a)(2)(C), Plaintiff discloses the following non-retained expert witness:

Expert Witness: Dr. [Full Name], M.D.
Address: [Practice Address]

Subject Matter: Dr. [Name] is expected to testify regarding the diagnosis, treatment, and prognosis of Plaintiff’s lumbar spine injuries sustained in the incident on [Date].

Summary of Facts and Opinions: Dr. [Name] treated Plaintiff from [Date] through [Date]. Dr. [Name] is expected to testify that Plaintiff suffered [specific injuries], that the treatment provided was reasonable and necessary, and that Plaintiff’s condition is expected to [prognosis]. Dr. [Name]’s opinions are based on personal examination and treatment of Plaintiff, including review of diagnostic imaging and medical records.

No signed report. No publication history, prior-testimony list, or compensation statement. What the summary cannot do is read like a witness list entry: naming the doctor and stopping there does not satisfy the rule.

What the Retained Expert’s Report Must Contain

The report attached to the retained-expert disclosure is where the work is. Rule 26(a)(2)(B) specifies six categories, and the expert must prepare and sign the report personally.¹

A complete statement of every opinion the expert will express at trial, with the basis and reasons for each. Vague conclusions do not satisfy this. Courts have struck reports where an expert disagreed with the opposing side’s analysis without explaining why, or flagged issues without identifying the specific facts.
The facts or data the expert considered, including material the expert reviewed but ultimately did not rely on. A study the expert read and rejected still goes on the list.
Any exhibits (charts, graphs, models, visual aids) the expert plans to use at trial to summarize or support the testimony.
The expert’s qualifications and a list of everything the expert has published during the previous ten years.
A list of every other case in which the expert testified at trial or by deposition during the previous four years.
A statement of the compensation the expert is being paid for study and testimony in this case, meaning the fee arrangement for this engagement, not the expert’s general rate card.

The prior-testimony list and compensation figure exist to support cross-examination on bias. The ten-year publication window lets the other side check whether the expert’s trial opinions line up with what the expert has written professionally.

What the Non-Retained Summary Must Contain

Two elements are required: the subject matter on which the witness will present evidence under Federal Rule of Evidence 702, and a summary of the facts and opinions the witness is expected to offer.¹ The subject-matter description should track the actual scope of the testimony. The summary should give real content: what the witness observed or treated, what opinions follow, and what those opinions rest on.

When the Disclosure Is Due

The default under Rule 26(a)(2)(D) is at least 90 days before the trial date or the date the case is set to be ready for trial. Rebuttal disclosures, offered solely to contradict or rebut opinions on the same subject matter identified by another party, are due 30 days after the other party’s disclosure.¹

In practice, the default rarely governs. Courts set their own deadlines through a Rule 16 scheduling order, and those deadlines usually fall well before the 90-day default.² Some districts key the expert deadline to the pretrial conference rather than the trial date. Check the assigned judge’s standing order and local rules early. A rebuttal expert who introduces new, independent opinions rather than responding to the other side’s expert can be struck as untimely under the original deadline.

Duty to Supplement

Serving the form is not the end of it. Rule 26(e)(2) imposes a continuing duty to supplement the information in a retained expert’s report and any deposition testimony the expert gave. If opinions change, new data arrives, or the original disclosure was incomplete, you have to update.¹

Supplementation is due by the time your Rule 26(a)(3) pretrial disclosures are due, which is at least 30 days before trial absent a different court order. You cannot wait until the eve of trial to spring a revised opinion; updates need to land in time for the opposing side to depose again or adjust their own expert.

What Happens if the Disclosure Is Incomplete or Late

Rule 37(c)(1) is the enforcement mechanism, and it is severe. A party that fails to identify a witness or provide the required information under Rule 26(a) cannot use that witness at trial, at a hearing, or on a motion. The exclusion applies unless the failure was substantially justified or harmless, and courts do not read those exceptions generously.³ A last-minute explanation about busy schedules or attorney oversight rarely qualifies.

The court may also inform the jury of the failure, order the offending party to pay reasonable attorney fees and expenses caused by it, or impose any other appropriate sanction. Where an excluded expert is central to a party’s case and no other evidence fills the gap, courts have entered default judgment or dismissed claims.

Content failures matter as much as timing failures. Courts routinely exclude reports that state conclusions without explaining reasoning, disagree with opposing experts without saying why, or flag issues without identifying specific facts. A report that reads like a placeholder is vulnerable to a motion to strike, which leaves the disclosing party in the same position as if nothing had been served.

1
Legal Information Institute. Federal Rules of Civil Procedure Rule 26
2
Legal Information Institute. Federal Rules of Civil Procedure Rule 16 – Pretrial Conferences; Scheduling; Management
3
Legal Information Institute. Federal Rules of Civil Procedure Rule 37