Marine Corps Job: MOS 0121 Personnel Clerk

MOS 0121: The Marine Corps Personnel Clerk

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The Military Occupational Specialty (MOS) code is a series of characters that the U.S. Army and the U.S. Marines use to identify particular jobs. MOS 0121 is designated as the personnel clerk. It's a PMOS and the rank range is from Sergeant to Private. 

This MOS was effectively terminated in June 2010 when it was merged into the newly created MOS 0111, Administrative Specialist, along with MOS 0151 and MOS 0193. This information is provided for historical reference. 

Duties and Responsibilities of the Personnel Clerk

The "01" portion of MOS 0121 designates personnel and administrative positions. Personnel clerks performed personnel and general administrative duties using manual and automated information systems, including postal service. They prepared documents, maintained personnel records, input audit, and retrieved pay and personnel information.

Typical duties included:

  • Auditing and making entries in individual service records
  • Auditing service records for required entries and documentation
  • Completion of various personnel and pay related forms and documents
  • Researching proper unit diary entry requirements
  • Reporting transactions into the Marine Corps Total Force System (MCTFS) via the unit diary 
  • Auditing and correcting feedback reports from systems
  • Preparation of individual pond and allotment requests
  • Performing other duties pertaining to pay and personnel administration as required

Personnel clerks might also have reviewed servicemembers' pay and allowances, processed service awards, and prepared dependency applications. 

Other duties and tasks performed could overlap those performed by administrative clerks, including preparation of naval correspondence and maintenance of correspondence files and directives.

You can refer to MCO 1510.53Individual Training Standards, for a complete listing of duties and tasks that were associated with MOS 0121. 

Job Requirements

Personnel clerks were required to have a thorough knowledge of the MCTFS, which encompasses the on-line Diary System (OLDS) and the Unit Diary/Marine Integrated Personnel System (UD/MIPS). 

Applicants were required to have a GT score of 100 or higher.

MOS 0121 was assigned upon completing the Personnel Clerk Course which was conducted at Camp Lejeune, North Carolina, or upon demonstrating satisfactory performance during VIOJT. They had to be able to type at a minimum speed of 25 words per minute prior to completion of the Personnel Clerk Course.

Applicants for MOS 0111, which merged MOS 0121 and other MOS codes, must currently meet similar requirements. A CL score of 100 or higher is required. Applicants must be U.S. citizens, and be eligible for secret security clearance. They must complete the Administrative Specialist Course at Camp Legeune. 

Related Department of Labor Occupation Codes 

  • Personnel Clerk 209.362-026
  • Clerk, General 209.562-010

Related SOC Classification Codes

  • Human Resources Assistants (except Payroll and Timekeeping) 43-4161
  • Office Specialist, General 43-9061

Related Marine Corps Jobs

  • Administrative Clerk, MOS 0151. This position was also merged into MOS 0111 in June 2010. These personnel acted as personnel and pay input clerks for the MCTFS. 
  • Personnel/Administrative Chief, MOS 0193. This position was also merged into MOS 0111 in June 2010. 
  • Postal Officer, MOS 0160
  • Personnel Officer, MOS 0170
  • Manpower Information Systems Analyst, MOS 0171

Much of the above information is derived from MCBUL 1200, parts 2 and 3.