DOD Instruction 4151.20 prescribes a “depot maintenance core capabilities determination process” to identify, in part, the (1) required core capabilities for depot maintenance and (2) planned workloads needed to support those capabilities. The instruction describes a series of mathematical computations and adjustments, which the military services use to compute their core capability requirements and to identify planned workloads needed to support these requirements. First, the services identify the weapon systems required to execute the Joint Chiefs of Staff contingency scenarios, which represent plans for responding to conflicts that may occur in the future. After the systems are identified, the services compute annual depot maintenance capability requirements for peacetime in direct labor hours to represent the amount of time they regularly take to perform required maintenance. Then contingency requirements and resource adjustments are made to account for applicable surge factors during the different phases of a contingency, such as preparation/readiness and sustainment. Further adjustments are made to account for redundancy in depot capability. For example, a service may determine that repair capabilities for specific systems maintained in military depots are so similar that the capabilities for one system can effectively satisfy the requirements of another. Core capability requirements are also adjusted when one service’s maintenance requirements will be supported by the maintenance capabilities of other services. During this process of identifying the systems for which they will be required to maintain repair capabilities, the services organize and aggregate their capability data by categories of equipment and technologies known as work breakdown structure categories. The work breakdown structure provides a way for DOD to break down a category of weapon system or equipment into subcategories of its parts at increasingly lower levels of detail. The work breakdown structure can be expressed at any level of detail down to the lowest-level part, such as a bolt. These categories, the programs or systems they include, and the lower-level elements or subcategories of defense materiel or equipment into which they are broken down are referred to by DOD as “levels of indenture.” There are eleven categories at the top level—“first” level—of the work breakdown structure. A first-level category summarizes information for an entire type of system or equipment, such as aircraft or ground vehicles. Table 1 shows the eleven first-level categories of the work breakdown structure. A first-level category can be broken down into second-level subcategories, which are the major elements that make up the system or equipment in the first-level category. For example, the first-level category for Aircraft can be broken down into the second-level subcategories for Airframes, Aircraft Components, and Aircraft Engines, which are major elements that make up an aircraft. The second-level subcategories can be further broken down into third-level subcategories, which are subordinate elements that make up the major elements in the second- level categories. For example, the second-level subcategory for Airframes is further divided into the third-level subcategories—different types of airframes, such as Rotary, Fighter/Attack, or Bomber. The subcategories can be further broken down to the lowest-level element of the system. Table 2 shows an example of the top three levels of the work breakdown structure for Aircraft. After the services have identified their core capability requirements, they identify the amount of available planned workload within the work breakdown structure categories and subcategories. DOD Instruction 4151.20 requires the military services to report biennially to OSD their core capability requirements and planned workloads, in accordance with a tasking memorandum issued for each reporting cycle. The instruction includes a worksheet that the services must fill out and submit to OSD. The worksheet calls for information to be organized by the work breakdown structure to various subcategory levels, mostly at the second-level subcategories. Appendix III provides a table listing these categories and subcategories. On April 9, 2012, OSD issued the tasking memorandum for the 2012 Biennial Core Report, which directed the services to use DOD Instruction 4151.20 as basic guidance and included further guidance on how to meet the requirement under Section 2464 to report this information to Congress. The memorandum augments the worksheet by adding another column for the estimated costs of performing the planned workloads at the first level of categories. The instruction and tasking memorandum also require the services to provide additional information when reporting shortfalls in planned workloads. If a military depot does not have sufficient workload to sustain the required level of capability that has been identified, a shortfall exists—in other words, the military depots have not been assigned the depot maintenance workloads that would enable them to sustain their identified core capability requirements. For example, a depot may have identified 10,000 direct labor hours of core capability requirements for ground vehicles but have only 4,000 hours of assigned depot maintenance work for ground vehicles. This depot will have a shortfall of 6,000 hours. The instruction requires that the services report on shortfalls by providing a description along with the worksheet, but the shortfalls are not calculated in the worksheet. DOD’s 2012 Biennial Core Report to Congress complies with two of the required reporting elements of Section 2464—including core capability requirements and planned workload—and partially complies with the third element by including mitigation plans, but not all detailed rationales for workload shortfalls. Further, the report provides complete information for each of the military services as aggregated to the top-level categories of the work breakdown structure. However, without providing clear explanations for the workload shortfalls that clarify why the services do not have the workload to meet core maintenance requirements, DOD’s report does not fully comply with Section 2464 and Congress lacks full visibility over DOD’s management of its shortfalls. OSD included in the report the requirements information expressed in direct labor hours for each of the military services. As reported, DOD’s total core capability requirements are about 70 million direct labor hours. Table 3 shows a summary of these core capability requirements by military service. Further, the information in DOD’s report on core capability requirements for each of the military services is complete as aggregated to the top-level categories of the work breakdown structure. Section 2464 requires the information in the Biennial Core Report to be organized by work breakdown structure; however, the statute does not specify at which category level of the work breakdown structure the information should be reported. To obtain the information needed to support the 2012 report, OSD’s memorandum directed the services to provide to OSD, among other things, information on core requirements and planned workloads at various lower-level subcategories. The memorandum also directed the services to provide, in any instance where core requirements exceed planned workloads, additional information on a plan to address workload shortfalls. Each of the services provided information in response to OSD’s memorandum. In response to the tasking memorandum, the services provided data on their planned workloads—the amount of available work used to maintain the required capability—by the top categories and various levels of subcategories in the work breakdown structure. In the report, OSD included complete information on the amount of planned workload that is available to maintain the required capability, expressed in direct labor hours at the top-level categories and the estimated cost of these workloads for each of the military services. As reported, DOD has a total planned workload of about 92 million direct labor hours at an estimated cost of about $12 billion. Table 4 shows a summary of these workloads. However, we identified an anomaly in the information reported for the Marine Corps. Its planned workload for the sea ships category was reported as 15,124 direct labor hours, without any reported cost. Because the estimated cost of this workload is reported as $0, it is unclear whether the cost for this work is accounted for in DOD’s report. OSD and Marine Corps officials stated that the workload hours to do these repairs are to be performed by the Marine Corps for the Navy. The Navy would reimburse the Marine Corps for the workload hours. However, the Navy’s submission for the report did not include these workload hours to be performed by the Marine Corps. Thus, these hours and cost were not clearly accounted for in the workload cost figures included in the report. OSD officials stated that they noticed the anomaly, but that their reporting time constraints precluded them from thoroughly investigating it. The report shows that the Navy had a workload of 8.9 million direct labor hours above the core maintenance requirement in the Sea Ships category. Because of this, OSD officials believed that the estimated workload was sufficiently covered and this error would not result in a shortfall. While DOD’s overall planned workloads exceed its core capability requirements, DOD’s report shows shortfalls in certain categories for the Army and the Air Force. The report includes complete information on shortfalls at the top-level categories and plans to mitigate all of the shortfalls identified in the report. However, the report does not include required information on the rationale for some of these shortfalls—the reasons why the services do not have the workloads to meet core maintenance requirements. Section 2464 requires that DOD include in its report “in any case where core depot-level maintenance and repair capability requirements exceed or are expected to exceed sustaining workloads,”—that is, in any case where there are shortfalls—“a detailed rationale for the shortfall and a plan either to correct, or mitigate, the effects of the shortfall.” Consistent with how it reported the core requirements and planned workloads, OSD aggregated the workload shortfalls under the top-level categories of the work breakdown structure for each service. The report shows that the Navy and Marine Corps did not identify any shortfalls in the workloads available to support their core capability requirements. In assessing the completeness of DOD’s report, we determined that the Navy and Marine Corps did not have workload shortfalls at any of the lower-level categories at which they provided information to OSD.