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Frequently Asked Questions
Usage of Person Months
Additional questions/concerns may be addressed to GrantsPolicy@od.nih.gov.

Initial Posting: April 21, 2006
Last Revised: February 20, 2013

  1. What is the definition of person months?
  2. How do you calculate person months?
  3. How are person months used when determining overlap and over- commitment?
  4. How does NIH enforce effort requirements in mechanisms, such as Ks, or in RFAs/PAs where minimum effort is stated?
  5. How should person months be reported in the non-competing progress report?
  6. How should person months be used in competing applications?
  7. When preparing the type 5 non-competing progress report, should the person months presented represent the total effort on the grant or only the person months to be charged to the grant?
  8. Is there any specific guidance for calculating person months for individuals with VA appointments?
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  1. What is the definition of person months?
    Person months - Is the metric for expressing the effort (amount of time) PI(s), faculty and other senior personnel devote to a specific project. The effort is based on the type of appointment of the individual with the organization; e.g., calendar year (CY), academic year (AY), and/or summer term (SM); and the organization's definition of such. For instance, some institutions define the academic year as a 9-month appointment while others define it as a 10-month appointment.
  2. How do you calculate person months?

    Conversion of percentage of effort to person months is straight-forward. To calculate person months, multiply the percentage of your effort associated with the project times the number of months of your appointment. For example:

    25% of a 9 month academic year appointment equals 2.25 (AY) person months (9 x 0.25= 2.25)

    10% of a 12 month calendar appointment equals 1.2 (CY) person months (12 x 0.10 = 1.2)

    35% of a 3 month summer term appointment equals 1.05 (SM) person months (3 x 0.35= 1.05)

    10% of a 0.5 FTE 12 month appointment equals 0.6 (CY) person months (12 x .5 X .1 = 0.6)


    Another example:

    If the regular pay schedule of an institution is a 9 month academic year and the PI will devote 9 months at 30% time/effort and 3 months summer term at 30% time/effort to the project, then 2.7 academic months and .9 summer months should be listed in the academic and summer term blocks of the application (9 x 30% = 2.7 person months; 3 x 30%= .9)

    See Percent of Time & Effort to Person Months Calculator (Excel - 20 KB).

  3. How are person months used when determining overlap and over- commitment?
    Resolution of overlap normally occurs at the time of award in conjunction with applicant institution officials, the principal investigator, and awarding Institute or Center (IC) staff.

    IC staff review other support and budget justifications (for modular applications) to determine if any personnel exceed 12 person months of funding. Personnel with over 12 person months would be the indicator of over- commitment (i.e. 12 person months translates to 100% effort).
  4. How does NIH enforce effort requirements in mechanisms, such as Ks, or in RFAs/PAs where minimum effort is stated?
    NIH staff review the person month's reported in the non-competing progress report. For instance, K awards require a minimum of 75% of full-time professional effort at the applicant organization, which must be spent conducting research career development and clinical research. This is based on a 12 month calendar year. If an individual has an academic year (AY) appointment, the required 9 person-months devoted to the K may be fulfilled in several ways.  Following are three examples:

    A. By devoting 100% effort during 9 academic months of the AY (1.0 x 9 = 9 person-months).

    B. By devoting 75% effort during 9 academic months of the AY (0.75 x 9 = 6.75 person-months), AND also devoting 75% effort during 3 summer months (0.75 x 3 = 2.25 person-months).

    C. By devoting 67% effort during 9 academic months of the AY (0.67 x 9 = 6 person-months), AND also devoting 100% effort during 3 summer months (1.0 x 3 = 3 person-months).
    No matter what calculation is used, when calculating using a metric other than calendar months, any combination of academic and summer effort must still equal the equivalent of 9 calendar months.
  5. How should person months be reported in the non-competing progress report?

    Person months reported in the Research Performance Progress Report should be reported in whole numbers (1-12).  Effort should be rounded to the nearest whole person month; e.g., 1.6 person months would be entered as 2 person months.  See NIH Research Performance Progress Report (RPPR) Instruction Guide (Chapter 6.4 Participants D.1).    

    Person Months reported in the PHS 2590 may be reported using decimals.  See instructions for the All Personnel Report (2.2.8 in the PHS 2590). 

    For all progress reports, person months less than one should only be reported if that individual is the PD/PI. 

  6. How should person months be used in competing applications?

    The SF424 (R&R) budget accommodates partial months up to two decimal places (e.g., 2.55 is an acceptable value) and less than a full month (e.g., .50 is an acceptable value).

    The person months used in the competing application, both in the detailed budgets or the budget justification,  should reflect the actual effort that an individual is proposing to devote to the project regardless of the compensation that is requested.  Effort and institutional base salary in detailed budgets are used to verify the requested salary.  Applicants should describe any differences or provide clarification for salary requested, as needed, in the budget justification. 

  7. When preparing the type 5 non-competing progress report, should the person months presented represent the total effort on the grant or only the person months to be charged to the grant?
    The person months presented should represent the total effort on the grant regardless of compensation. The total effort devoted to a grant does not always represent the actual salary that is requested.
  8. Is there any specific guidance for calculating person months for individuals with VA appointments?
    When dealing with individuals that have a joint University/VA appointment, the grantee should focus first on the University appointment when they are figuring out person months.  If VA effort is also devoted to the project, the grantee should continue to reflect the effort on a separate line item of the personnel section. 

    For example: 10% Univ. appointment would be listed as 1.2 mos on one line of the budget &   15% VA appointment would be 1.8 mos on another.  Or if this is a Modular grant then the grantee should reflect this information in the budget justification identifying his/hers appointment type (i.e. calendar, academic and/or summer months).

    When dealing with the concept of total professional effort, it is still appropriate to reflect overall responsibility proportional totals as percentages of total.  This would be acceptable since you are potentially dealing with clinical, administrative, teaching and/or research responsibilities within each appointment.   However, grantees have the flexibility to manage this process in the manner that fits their institutional practice as long as consistency is applied. 

    With regard to other support for individuals with University/VA appointments, this does need to be reflected as calendar, academic and/or summer months.  Grantees should continue to reflect separately any University vs. VA effort devoted.

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