NIH Appendix Policy 2026: What's Allowed, What Gets Rejected, and When to Submit Nothing

Why NIH Appendix Rules Catch Applicants Off Guard

The appendix used to be a place where applicants could extend their research strategy. Papers in press, supplemental figures, extra data — all of it went in. NIH closed that door progressively over the last decade and a half, and the rules are now substantially stricter than many applicants who learned grant writing before 2012 expect.

What catches people is that appendix rules are not widely covered in grant-writing workshops, which tend to focus on Specific Aims, Significance, Innovation, and Approach. Someone preparing a first R01 may not encounter the appendix rules until they're inside ASSIST with a submission deadline 48 hours away, looking at the appendix upload interface and wondering what goes there. The answer, more often than applicants expect, is: nothing.

The appendix is an optional component of NIH applications. It is not required for most activity codes, and reviewers are not instructed to weight it in their scoring. That does not mean it is useless. It means the threshold for including anything should be genuinely high — the materials must be explicitly allowed, must be content reviewers cannot reasonably find elsewhere, and must not be an attempt to route around the page limits of the research strategy.

What NIH Policy Actually Permits in 2026

NIH's current appendix policy restricts allowable materials to a narrow set of categories. The general rule is that appendix materials must either be required by the funding opportunity announcement (FOA) or fall into a small list of permitted types. Here is what consistently qualifies:

One thing worth noting: some program-specific FOAs for training grants, cooperative agreements, and other mechanisms may specify additional allowed items or have their own appendix requirements that differ from the general R-series rules. Always read the appendix section of your specific FOA before finalizing what you include, not just the general NIH appendix guidance.

What You Cannot Include (and the Reasoning Behind It)

The list of what is not allowed is, in practice, as useful as the list of what is. The most common category of prohibited materials is publications and manuscripts.

Prior to around 2010, applicants routinely attached published papers and accepted manuscripts. This gave them an informal way to show reviewers depth of work that would not fit in the biosketch or in the preliminary data section. NIH phased out this practice for real reasons: it created an uneven playing field where applicants at high-publishing institutions could signal productivity in ways that early-career researchers and those at primarily undergraduate institutions could not match as easily. Published papers must now be cited in the bibliography. The content itself is not appendix material.

Manuscripts in press or under review similarly cannot go in the appendix. If a paper has been accepted but not published, you cite it as "in press" in your bibliography. The manuscript text itself is not allowed.

Figures, graphs, and data tables that belong in the Research Strategy are also not allowed. This is the most tempting violation, because the Research Strategy has strict page limits — 12 pages for most R01s, 6 for R21s — and researchers often have more preliminary data and figures than fit. The correct response to a full research strategy is to cut and prioritize, not to route the overflow into the appendix. Reviewers who find this kind of material may flag it explicitly as a page-limit workaround.

Other prohibited materials include curriculum vitae (covered by the biosketch), any reprints of published work, and any content the FOA has not specifically authorized. If you are uncertain whether a specific item qualifies, the safest path is to contact your grants management office or program officer before the deadline — not to assume it's fine and find out afterward.

When Reviewers Actually Look at Appendix Materials

Reviewers are not required to read appendix materials. The NIH peer review guidance makes clear that appendix content should not substitute for or supplement the scored sections. In practice, this means two things, and understanding the distinction matters for strategy.

When your appendix contains materials that reviewers genuinely need to evaluate your application — the actual questionnaire instruments a survey study will use, for example — conscientious reviewers will look at them. A study whose feasibility depends partly on the quality of the measures is a legitimate case for appendix use. Reviewers assigned to that application typically do examine those instruments.

When your appendix contains materials that should have been in the research strategy but were not — additional figures, extended data tables, more detail on methods than the page limit allowed — reviewers will not give you credit for them. Some will flag the inclusion explicitly as a page-limit workaround, which can affect the Approach score or Overall Impact in ways you do not want. The appendix is not a backstop for a tight research strategy.

One additional detail: appendix materials are shared with your three assigned reviewers but are generally not forwarded to second-level review by the NIH Advisory Council. Anything that matters for a program officer's funding decision needs to be in the main application, not in the appendix.

Strategic Decisions: When to Submit Nothing

For most R01, R21, and R03 applications in basic and translational research, the right appendix strategy is to include nothing. This is not a failure mode. It is a reflection of what NIH's policy is designed for. If your study does not use survey instruments, does not involve human subjects consent forms specific enough to warrant inclusion, and your FOA has no appendix requirements, you have no legitimate appendix content.

Submitting an empty appendix is cleaner than submitting anything that might raise questions. It does not signal anything negative to reviewers. It means your application does not have content that requires the appendix component, which is true for many rigorous applications.

The calculus changes for specific research types. Human subjects studies that use standardized or novel instruments benefit from including those instruments because reviewers evaluating feasibility and rigor will want to see the actual measures. Studies operating in multilingual communities benefit from showing the translated materials. Studies involving complex data collection protocols may benefit from including a blank data collection form that the research strategy description alone cannot adequately convey to a reviewer unfamiliar with your specific methods.

Before adding anything to the appendix, apply two tests: Is this item explicitly allowed by NIH policy or my FOA? And would a reviewer's evaluation of my application genuinely improve by seeing it? Both should be yes before you include it. If you're reaching to justify an item under one test or the other, that's a signal to leave it out.

Common Appendix Mistakes That Slow Down Applications

The most frequent mistake is attaching publications. Researchers who learned grant writing a decade or more ago often default to this out of habit — it used to be standard practice, and old habits are hard to break when you're busy. In the current system, attached papers are stripped from the application before it reaches reviewers. If you want reviewers to know about a key publication, cite it in the bibliography and reference it substantively in the preliminary data or approach sections of your research strategy. That is the correct path, and it keeps the credit inside the scored section where it actually influences your score.

The second common mistake is including an appendix at all when the FOA says not to. Some targeted FOAs and program announcements explicitly state that appendices are not accepted or that any submitted appendix will be removed. Reading the appendix section of the specific FOA — not just the general NIH instructions — before uploading anything is necessary, not optional.

A third mistake is routing a letter of support into the appendix rather than its proper section. This one is understandable — ASSIST can be confusing about where specific items belong — but it has real consequences. Letters routed incorrectly may not reach reviewers in usable form. Reviewers who expect a letter from a key collaborator and cannot find it will mark it as absent in their review, which can affect the Investigator or Approach scores depending on the role that collaborator plays.

Finally, some applicants include appendix materials in formats that ASSIST does not accept or that exceed file size limits, triggering submission errors in the 48 hours before a deadline. Appendix files must be submitted as PDFs in most cases. Testing the upload in ASSIST well before the deadline — not the night before — catches these problems when you still have time to fix them.

A Pre-Submission Appendix Checklist

The 48 hours before submission is a poor time to learn the appendix rules. Running through this checklist two to three weeks out saves the kind of stress that produces errors.

Frequently Asked Questions