Caution: Roles Determine Eligibility and Other Requirements

Funding News Edition: February 01, 2017
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The scientific community uses many terms to describe different roles on a project. However, some terms aren’t used by NIH or are terms that cause confusion. The terminology you use might affect your eligibility for a funding opportunity announcement (FOA), as well as the information required in a grant application and to make an award.

As you discuss the roles your colleagues can play in support of your planned research, use the guide below to ensure you have a shared understanding.

Here we cover five role-related terms that have caused confusion: co-PI, co-investigator, collaborator, consultant, and other significant contributor. At the end of the article, we offer advice on how to maximize clarity for reviewers.


Do not use the term co-PI. Because NIH doesn't recognize it as a role, it causes confusion since it’s unclear whether you mean PI on a multiple-PI award or co-investigator. And that confusion could affect your application; some FOAs have eligibility or level of effort requirements that affect only PIs.

Note that assigning someone the role of "Co-PD/PI" will not identify the application as a multiple PD/PI application. Colloquially, we sometimes hear the term co-PI used to indicate your fellow PIs on a multiple PI grant. But in that case, they should still be called PIs, not co-PIs.

You may have noticed that co-PI is one of the options listed on the SF 424 forms (standard grant application form). That's because other agencies use that role, but we don't.


Co-investigator is a term commonly used by the scientific community and in grant applications. For NIH’s official definition, go to Glossary & Acronym List.

This role describes those involved with the PI in the scientific development or execution of the project, but they just don’t quite rise to the level of being principal investigators. They should be listed as key personnel.

Do not use “co-investigator” when you mean a PI on a multiple-PI application.

When deciding whether your application should have multiple PIs or a single PI with one or more co-investigators, there are no rules or percentages to go by. The decision should be based on the research proposed to ensure optimal management of the project. Assuming your chosen funding opportunity allows either option, we suggest discussing this with your colleagues and business officials.


Collaborators always play an active role in the research, and the position is sometimes defined interchangeably with co-investigator. As a loose guideline, think of a collaborator as a scientist whose distinct expertise complements your own while a co-investigator shares your area of expertise and therefore contributes in guiding the scientific direction of the overall project. One provides unique expertise, the other umbrella expertise.

Still, many areas of science have their own expectations for each of these roles. So long as the role of each contributor is thoroughly explained in your Personnel Justification and the Letters of Support, your choice between the titles of "co-investigator" and "collaborator" won't be a point of contention for reviewers.

Collaborators are typically listed as key personnel. They may get part of their salary paid from the grant in person months. Collaborators at other institutions could have their salary paid through a consortium agreement (also called a subaward).

Some senior-level collaborators may choose to work part-time for credit (e.g., the potential of future publications), rather than pay.


A consultant provides advice or services and may participate significantly in the research. For NIH’s official definition, go to Glossary & Acronym List.

Often he or she helps fill in smaller gaps by, for example, supplying software, providing technical assistance or training, or setting up equipment.

List consultants as key personnel only if they contribute substantively and measurably to the scientific development or execution of a project.

Consultants do not receive a salary from your grant but may receive a fee as a transaction for their service.

Other Significant Contributors

When you have people who commit to contributing to the scientific development or execution of the project but do not commit any measurable effort (i.e., person months) to the project, their role would be other significant contributor (OSC).

OSCs are typically presented at effort of “zero person months” or "as needed." If their effort is measurable, you may not list them as OSCs.

Biosketches are required for all personnel identified in the application as OSCs. However, other support information is not required. Consultants should be included as OSCs if they meet the definition.

In Conclusion

To maximize clarity for your reviewers when you apply, make sure your Personnel Justification and Letters of Support thoroughly describe what each person will be doing. Your reviewers need to be able to judge whether there is sufficient expertise to conduct the project.

Too often, we see Letters of Support that are enthusiastic and indicate a willingness “to collaborate” but don't provide enough details about the exact role of the person in the project. When that happens, we have to request additional information from you before we can make an award.

For more on the roles people can play in your project, check out Consultants, Collaborators, & Subawards.

You could also discuss how to address gaps in expertise with your program officer or local mentors.

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