Letter of Intent (NIH)

A Letter of Intent (LOI), in the context of an NIH grant application, was a short, non-binding pre-application notice — typically one page — that some NIH funding opportunities asked a prospective principal investigator (PI) or their institution to submit roughly 30 days ahead of the actual application due date. It named the PI, the participating institution(s), and the number and title of the funding opportunity the applicant intended to respond to. Critically, an LOI never committed the sender to actually submitting a full application, was never scored or factored into peer review, and did not count against any page limit on the eventual application itself.

Policy update, read this first: Effective December 3, 2025, NIH eliminated the Letter of Intent process across its standard application policies via Guide Notice NOT-OD-26-019, “Updated Application Policies: NIH Administrative Burden Reduction Effort — Removal of Requirements for Letters of Intent and Unsolicited Applications Requesting $500,000 or More in Direct Costs.” NIH will no longer request or accept LOIs as part of the application process, and any LOI submitted will not be acknowledged or reviewed by the relevant Institute, Center, or Office (ICO) or NIH’s Center for Scientific Review (CSR). NIH’s stated rationale is that, with peer review increasingly centralized through CSR, the LOI had stopped serving its original purpose of helping individual ICOs forecast reviewer workload. The rest of this entry describes what the NIH LOI was and how it worked while the practice was in effect, since the term still appears throughout older guidance, university research-office pages, and search results — treat any instruction to submit one as outdated unless a specific, currently open funding opportunity explicitly says otherwise.

Why NIH requested letters of intent

Before the December 2025 policy change, NIH described the LOI’s purpose plainly in the funding opportunity announcements that requested one: it let NIH staff estimate the potential peer review workload for a competition and, where useful, begin recruiting reviewers with the right expertise ahead of the actual application deadline. Because NIH runs its extramural review through study sections staffed by outside scientific experts, knowing roughly how many applications to expect — and in which scientific areas — helped Scientific Review Officers assemble an appropriately sized and appropriately expert study section before the applications themselves arrived. An LOI was requested by some Notices of Funding Opportunity (NOFOs) and not others; it was never a universal NIH requirement across every mechanism.

What made an LOI non-binding

“Non-binding” meant exactly what it says: submitting a letter of intent did not obligate the sender to submit the corresponding application, and failing to submit one did not disqualify an otherwise-eligible applicant from applying to a NOFO that requested (rather than required) an LOI. NIH’s own guidance was explicit that an LOI was “not required, not binding, and does not enter into the review of a subsequent application.” A prospective applicant who changed their mind, missed the LOI’s own informal deadline, or decided late to apply after all was still free to submit a full application by the actual, separate application due date, provided the NOFO didn’t state otherwise for a specific competition.

Typical contents and timing

Where NIH requested one, a Letter of Intent was short — commonly a single page — and typically included the descriptive title of the proposed research, the NOFO number it responded to, the name and institutional affiliation of the PI (and any co-PIs on a multi-PI application), and the names of other key senior/key personnel and participating institutions. NIH generally suggested submitting an LOI roughly 30 days before the application’s own due date, though the exact suggested lead time was set by each individual NOFO rather than being fixed NIH-wide. LOIs were typically submitted by email directly to the contact named in the NOFO’s Letter of Intent section, not through eRA Commons or ASSIST — a meaningfully lighter-weight process than submitting the application itself, and part of why it never counted against the application’s own page limits.

LOI vs. a full application, and vs. a letter of support

An NIH Letter of Intent is easy to confuse with two other documents that sound similar but serve entirely different functions:

• A full grant application is the actual, scored submission — specific aims, research strategy, budget, and the full package of supporting documents described in CASRAI’s How to Apply for a Research Grant guide. An LOI was never a substitute for it, never scored, and orders of magnitude shorter.
• A letter of support is a document from a collaborator, consultant, or partnering institution endorsing a specific applicant’s proposed project, submitted as part of (or alongside) the full application itself. An LOI, by contrast, was sent by the prospective applicant or their institution to NIH, before the application existed in submittable form — not an endorsement attached to it.

Worked example (illustrative)

Before December 2025, a funding opportunity announcement for an R01 mechanism that requested an LOI might have included a line reading: “Prospective applicants are asked to submit a letter of intent that includes the following information: descriptive title of the proposed research; name, address, and telephone number of the PI; names of other key personnel; participating institutions; and the number and title of the NOFO.” An applicant intending to respond would send a one-page email to the contact listed in that NOFO roughly a month before the application deadline, then proceed to prepare the full application regardless of what they wrote in the LOI — the two documents were not otherwise linked.

Counter-examples

• A researcher who submits a complete NIH application without ever having sent a letter of intent is not at any procedural disadvantage: an LOI was never scored, and — as of December 2025 — NIH’s general application policy no longer requests or accepts one at all, so its absence from an application package is not itself a compliance issue.
• A letter attached to the application package that a collaborator writes to endorse the proposed project is a letter of support, not a letter of intent — see CASRAI’s Letter of Support for a Grant Proposal guide for what that document needs to include.
• A pre-proposal or letter of intent requested by a private foundation (common for many non-federal funders) follows the same general concept but is not the same instrument as an NIH LOI, and foundations set their own rules for whether it is binding, scored, or a gate to a full invited application — always check the specific funder’s process, as covered generally in CASRAI’s How to Apply for a Research Grant guide.

Related CASRAI resources

• How to Apply for a Research Grant: The Application Process, Step by Step — where the LOI fit into the broader application timeline
• Components of a Grant Proposal: What Every Section Needs to Do
• Limited Submissions: Managing Internal Competitions for Restricted Funding Opportunities — a different pre-application step, used when a funder caps the number of applications per institution
• Letter of Support for a Grant Proposal: What to Include
• NIH Grants: An Overview
• Grants Management pillar page