NIH Grants: Types, Eligibility, and How to Apply

An NIH grant is federal funding from the National Institutes of Health for biomedical, behavioral, and health-related research. NIH awards it through standardized funding mechanisms called activity codes, such as the R01 research project grant, and in almost every case the money goes to an institution (a university, hospital, research organization, or, for SBIR and STTR, a small business) on behalf of a named principal investigator. Every application is scored by peer review before any funding decision is made.

NIH is part of the Department of Health and Human Services and is funded by annual congressional appropriations. It is made up of 27 institutes and centers, and Congress kept all 27 in the fiscal year 2026 appropriation, rejecting a proposal to consolidate them into eight. Each institute has its own mission and budget, so the first decision is not how to write but where your project belongs.

What changed at NIH in 2025 and 2026

If your mental model of NIH comes from a few years ago, several rules no longer apply. These are the changes that affect how you plan an application today:

• Simplified peer review. For most research project grants with due dates on or after January 25, 2025, reviewers no longer score five separate criteria. They score Importance of the Research (significance and innovation) and Rigor and Feasibility (the approach) on the 1 to 9 scale, and rate Expertise and Resources (investigators and environment) only as sufficient or not sufficient.
• No more paylines. Under NIH's Unified Funding Strategy, effective with the January 2026 council round, institutes do not fund by a published percentile cutoff. Review scores still matter most, but each institute weighs them alongside its priorities and portfolio, and NIH publishes each institute's funding approach on a central Funding Decisions page.
• An application cap. Since September 25, 2025, NIH accepts no more than six new, renewal, resubmission, or revision applications per principal investigator (including multiple principal investigators) across all council rounds in a calendar year. Training (T) awards and R13 conference grants are excepted; check the current Grants Policy Statement for any other exceptions.
• Originality and generative tools. Under the same 2025 policy, NIH will not consider applications substantially developed by generative tools, or containing sections substantially developed that way, to be the original ideas of the applicant, and it can act on detected use after award.
• Where opportunities are posted. NIH now posts funding opportunities on Grants.gov rather than in the NIH Guide, relies more on broad parent announcements, and lists institute research priorities as "highlighted topics" that can be added at any time.
• New biosketch. Applications due on or after January 25, 2026 must use the Common Form biosketch plus an NIH supplement, built in SciENcv. Our annotated NIH biosketch example walks through the new format.

NIH has amended several of these policies more than once. Before you start, read the funding opportunity and any notices it references, because the opportunity governs if it differs from general guidance.

The main activity codes

A handful of activity codes cover most of what applicants pursue:

Budget limits are set in each funding opportunity and some institutes cap them lower, so confirm the figure in the opportunity you apply to. The Research Strategy runs 12 pages for an R01 and 6 pages for an R21 or R03 in the standard instructions.

Choosing the wrong code is a real cause of poor scores. An R01 without the preliminary data to support it reads as premature, while an R21 that proposes three years of work reads as mis-scoped. Our breakdown of why grant applications get rejected covers this pattern and others. If you are a company rather than a lab, the small-business track works differently; start with our guide to the SBIR proposal process.

Who can apply

For most NIH research grants the applicant is the organization. A university, hospital, or research institute registers in SAM.gov, Grants.gov, and eRA Commons, submits the application, and is accountable for the funds, while the principal investigator directs the science. An independent researcher without an eligible institutional home generally cannot hold an R01. Fellowships are applied for by the trainee with a sponsoring institution, and SBIR and STTR awards go to the for-profit small business itself. For the registrations every federal applicant needs, see how to register in SAM.gov and Grants.gov.

From submission to award

NIH has three standard receipt cycles a year. Standard due dates for new R01 applications fall on February 5, June 5, and October 5, and the R21 and R03 dates fall on the 16th of the same months; resubmissions and some activity codes use other dates, so check the opportunity. From submission to the earliest possible start date usually takes about nine months.

1. Referral. NIH's Center for Scientific Review assigns the application to a study section and to one or more institutes.
2. Study section review. Typically three assigned reviewers write critiques. Roughly the more competitive half of applications are discussed at the meeting and receive an overall impact score from 10 to 90 (lower is better); the rest are marked not discussed.
3. Council review. The institute's advisory council provides a second level of review.
4. Funding decision. The institute decides which applications to fund within its budget and priorities, under the Unified Funding Strategy.

Scores appear in eRA Commons shortly after the study section meets, and the summary statement with the full critiques follows. If you are not funded, that summary statement is the basis for a resubmission, which has a one-page introduction responding to the critiques.

Finding a home for your project

The cheapest preparation step is free. NIH RePORTER lets you search funded awards by keyword, institute, activity code, and study section. Use it to answer three questions before you write:

• Which institute funds work like yours, and at what budget scale?
• Which study section reviewed those awards, so you know your likely readers?
• Which funded investigators are closest to your idea, and what makes your project different?

Then read the institute's highlighted topics and contact the program officer listed on the relevant opportunity with a short summary of your aims. Program officers can tell you whether the work fits their portfolio, which no amount of writing can fix later. For reading an opportunity closely, see what a NOFO is and how to read one.

Where applications are won or lost

Under the simplified framework, the approach sits in its own scored factor, so rigor and feasibility carry as much weight as the importance of the question. In practice the pieces that move scores are:

• The Specific Aims page. Every panel member reads it, and the assigned reviewers return to it while scoring. Our guide to writing Specific Aims, paragraph by paragraph covers the method, and our worked Specific Aims pages show it executed for R01, R21, K, and SBIR applications.
• Aims that do not depend on each other. If a null result in Aim 1 makes Aims 2 and 3 meaningless, reviewers will call it a design risk.
• An approach that names its own pitfalls. Alternative strategies for the likeliest failure points read as rigor, not weakness.
• Effort and budget that match the work. NIH budgets express effort in person-months, split into calendar, academic, and summer months for faculty on nine-month appointments; see level of effort in a grant budget.
• A team that visibly covers every method. The Expertise and Resources factor is a pass or fail gate, so a missing capability should be covered by a named collaborator.

If your work could also fit the National Science Foundation, note that its review criteria and proposal structure differ substantially; our guide to NSF grants explains how.

When you want specialist eyes on the aims and approach before you submit, our NIH grant writing service starts with the aims page, where the most leverage sits.