Mixed Series Positions in Federal Employment

Determine a position’s series by identifying the highest-graded work performed most of the time, considering paramount knowledge, recruitment sources, promotion paths, and organizational purpose when duties span multiple occupational series.

Classifying mixed series positions requires careful evaluation of duties spanning multiple occupational series. Determining the correct series depends primarily on the work that establishes the grade and several key factors, including required knowledge and organizational function.

Key Insights

  • Allocate positions to a single series when duties fall under one classification standard; otherwise, use the series tied to the grade-determining work.
  • When no single series clearly applies, consider paramount knowledge, recruitment sources, promotion lines, and the position’s purpose to guide classification.
  • Use O1 “general” series, such as GS-301 or GS-801, when duties span multiple functions within one occupational group, and no more specific series applies.

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All right, now let's look at mixed series positions. And so, some mixed series situations may include positions involving work covered by a combination of series. If a position involves work in a combination of areas covered by a single classification standard, then the position is allocated to that series.

And so, how do you determine mixed series positions? The work that determines the grade determines the series. If no combination or series or one series is available, and the work of the position falls into more than one series, consider these things together. The paramount knowledge that is required for the position, the recruitment sources, the lines of promotion, the organizational functions, and the reasons for the position's existence.

And so, you want to make sure that in most cases, the work that determines the grade determines the series. And so, the highest level of work that determines the grade also determines the series. And so, I'm going to give you some examples.

And so, positions involving a combination of series. And so, you may have a GS-305 mail and file series, which covers both mail and file work. The GS-341 administrative officer series, which covers a variety of management services such as HR, financial services, office services, contracting and procurement, and program services, and management and analysis work.

And so, if you use the O1 series, many occupation groups will have an O1 series that covers positions that cover two or more disciplines within that series. And so, if you think of the 301, we call that the catch-all series. It covers multiple functions within the 301 occupational group.

And so, some other examples include the GS-801 general engineering series, the 1001 general arts and information series, and the 1701 general education and training series. And so, if there's no O1 series, again, available, then you want to look at the work that's performed the majority of the time. And so, you want to consider some factors together.

Since no single series always results in the most logical decision, you want to exercise professional judgment when determining the most appropriate series for the position. Just remember, in most cases, the work that determines the grade determines the series. I'm going to say that one more time.

The work that determines the grade determines the series. And so, let me give you another example. And so, to accomplish the mission of responding to emergency conditions, an agency has a position that involves both the GS-810 grade 12 engineering work 65% of the time and the GS-1102 grade 11 contract specialist work 35% of the time.

Employees in these positions must be qualified in both occupations. However, since the engineering knowledge is paramount and the recruitment must be from candidates that meet the engineering qualifications, the positions are classified to the engineering series rather than the contracting series. The grade of the position is GS-12 since the majority of the work is performed at that level.

All right. So, we have covered mixed series and mixed grade. And so, we want you to go to exercise 2-1.

Complete the following cases and answer the questions for cases 1 and 2. Explain your answers for each of the cases. Have fun!

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Sineta Scott Robertson

Sineta Scott Robertson is an instructor at Graduate School USA, teaching in Human Resources with an emphasis on federal position classification since 2018. With nearly four decades of distinguished service in federal Human Resources leadership, she is a seasoned executive and educator recognized for her expertise in Title 5 HR, workforce planning, organizational design, and employee engagement.

She has dedicated her career to advancing strategic human capital management across Cabinet-level agencies, serving as both a transformative leader and trusted advisor to senior executives and policymakers.

Throughout her federal career, Sineta has held pivotal leadership roles at the U.S. Department of Transportation, Department of Housing & Urban Development, and Department of Agriculture, where she guided national HR policy, labor relations, workforce innovation, and program oversight. Notable achievements include leading the Department of Transportation’s efforts to become a “Telework Ready” agency, implementing its HR Accountability and Pathways Programs, and spearheading process improvements that significantly reduced error rates and improved performance management outcomes.

In addition to her government service, Sineta has extended her expertise to the classroom as an Adjunct Human Resources Instructor with Graduate School USA, where she equips HR professionals, supervisors, and executives with practical and technical knowledge in federal human resources systems, policies, and practices.

In 2014, she founded Perspectives for Peace, LLC, a consulting and Christian coaching practice. Through this work, she partners with organizations to strengthen HR effectiveness and provides faith-based executive and life coaching, helping leaders align purpose, performance, and peace.

Her career is marked by a commitment to people—helping agencies build high-performing, motivated workforces while guiding individuals to unlock their potential and live with clarity of purpose.

Sineta holds a master’s degree in Christian Counseling from Newburgh Theological Seminary (2024) and is a Doctoral Candidate in Christian Counseling (expected 2026). She also earned her Bachelor of Science in Biblical Studies from Washington Baptist Theological Seminary.

A respected professional, mentor, and faith-driven leader, Sineta Scott Robertson continues to merge her passion for organizational excellence with her calling to serve others through coaching, teaching, and ministry.

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