DOD uses two related but distinct terms to differentiate between individual service members’ time away from home versus unit deployments: Perstempo: The amount of time individual service members serve on official duty at a location or under circumstances that make it infeasible for them to spend off-duty time in the housing in which they reside including for deployment events, such as operations, exercises, and unit training, and non-deployment events, such as individual training and hospitalization. Operational tempo: The rate at which military units are involved in all military activities, including contingency operations, exercises, and training deployments. Operational deployments are one type of deployment event, but do not account for all of the time individuals spend away from home. As a result, individual perstempo is typically higher than operational tempo. The National Defense Authorization Act for Fiscal Year 2000 included a provision that required the Under Secretary of Defense for Personnel and Readiness to monitor the perstempo of the armed forces, and required DOD to manage the number of days its service members are deployed. Section 991 of title 10 defines “perstempo” as the amount of time members of the armed forces are engaged in their official duties at a location or under circumstances that make it infeasible for a member to spend off-duty time in the housing in which the member resides. The law establishes thresholds for deployment perstempo events—220 deployment perstempo days in a 365-day period and 400 deployment perstempo days in a 730-day period. The law also requires the Secretary of Defense or a delegated official to approve when service members exceed these thresholds, and requires DOD to establish a system for tracking and recording the number of deployment perstempo days for each member of the armed forces. Additionally, DOD obtained the statutory authority to pay service members an allowance for lengthy or numerous deployment perstempo events. Congress authorized DOD to waive the deployment perstempo thresholds and recordkeeping requirement, which in turn would prohibit the payment of high-deployment allowances, if the department found that the waiver is necessary in the interests of national security. See figure 1 for a timeline of these and additional congressional and DOD actions related to perstempo. In the aftermath of the September 11th attacks, the Deputy Secretary of Defense issued a memorandum that suspended the requirements to manage deployment days for service members and the payment of high- deployment allowances. As a matter of DOD policy, the memorandum did not suspend the recordkeeping requirement included in section 991 of title 10. In May 2001, the Under Secretary of Defense for Personnel and Readiness issued an instruction that described policy, responsibilities, procedures, and information requirements for reporting of active duty military personnel records, and this instruction included requirements for perstempo reporting. In 2009, the Under Secretary of Defense for Personnel and Readiness issued another instruction, DOD Instruction 1336.07, that was focused on the reporting of perstempo and the instruction identifies responsibilities, procedures, and information- reporting requirements for perstempo. In particular, DOD Instruction 1336.07 states that the: Under Secretary of Defense for Personnel and Readiness is responsible for providing overall policy guidance for DOD reporting of all perstempo events; Director of the Defense Human Resources Activity, through the Defense Manpower Data Center, is required to maintain a perstempo events database; Secretaries of the military departments are responsible for implementing these reporting requirements whenever service members participate in or are associated with a perstempo event or activity; and services must record all perstempo events, including deployment events such as operations, exercises, and unit training as well as non- deployment events such as individual training and hospitalization. In November 2013, the Under Secretary of Defense for Personnel and Readiness issued a memorandum conveying that the amount of time that a unit, detachment, or individual service member can be operationally deployed should be equal to or less than the amount of time not deployed. Operational deployments are one of the deployment perstempo events. The memorandum also requires the military services to register perstempo events. DOD’s stated intent in the memorandum was for commanders at every level to ensure that individual service members, regardless of unit assignment, are not repeatedly exposed to combat, do not experience disproportionate deployments, and do not spend extended periods of time away from home unless required by operational necessity. We have reported on perstempo and readiness in multiple prior reports. For example, in 1996 we reported on DOD’s actions to mitigate the impact of high perstempo, including efforts to create systems for measuring perstempo. We reported that DOD had not issued regulations for the long-term management of perstempo and had not directed the services to have policies that limit perstempo. Further, we reported that it was difficult for DOD to determine the amount of perstempo time for military personnel for multiple reasons, including that the services had different systems for tracking deployments. We recommended that DOD (1) issue guidance on managing perstempo that states whether each service should have a goal for the maximum perstempo time for personnel and (2) issue regulations defining the minimum perstempo data that each service must collect and maintain. DOD concurred with these recommendations and, as we noted earlier, the Under Secretary of Defense for Personnel and Readiness issued DOD Instruction 1336.5 in 2001 that described policy, responsibilities, procedures, and information requirements for perstempo reporting. However, our recommendation has not been fully implemented because DOD Instruction 1336.5 did not include guidance on managing perstempo that states whether each service should have a goal for the maximum perstempo time for personnel, as discussed later in the report. In 2007, we found that Army and Marine Corps perstempo data were incomplete and inaccurate due to a lack of quality controls. We recommended that the Office of the Under Secretary of Defense for Personnel and Readiness provide guidance that directs the Army and Marine Corps to develop quality control procedures for validating the accuracy of the perstempo data. DOD concurred with our recommendation and in 2009 issued DOD Instruction 1336.07; however, our recommendation has not been fully implemented because the instruction did not provide guidance that directs the Army and Marine Corps to develop quality control procedures for validating the accuracy of perstempo data, as discussed later in the report. Finally, our work has identified several challenges with readiness rebuilding due in part to the high pace of operations that drives up perstempo. In 2016, we reported that the global security environment will likely continue to require significant reliance on U.S. military forces to respond to a range of demands, and the military services have attributed low readiness levels to increasingly long and frequent deployments, reduced force structure, and continuing and emerging demands. We also reported that DOD implementation and oversight of department-wide readiness rebuilding efforts did not fully include key elements of sound planning. We recommended, among other things, that DOD and the services establish comprehensive readiness goals and strategies for implementing them, as well as associated metrics that can be used to evaluate whether readiness recovery efforts are achieving intended outcomes. DOD generally concurred with our recommendations and the department has taken some steps to improve the readiness of the military forces, but it has not yet taken steps to fully implement our recommendations. DOD, service, and SOCOM policies vary in identifying specific and measurable thresholds on perstempo for individual service members. DOD policy focuses on time away for deployment, which is a part of perstempo but does not encompass the full range of activities that can take service members away from home. Specifically, a 2013 memorandum from the Under Secretary of Defense for Personnel and Readiness states that individual service members should not be deployed longer than they are at their home station. However, the memorandum describes perstempo only in general terms—stating that individual service members should not serve extended periods of time away from their homestation unless required by operational necessity. An official in the Office of the Under Secretary of Defense for Personnel and Readiness acknowledged that the department has not defined DOD’s perstempo threshold—to encompass non-deployment events—in specific and measurable terms and has not directed the services to establish such perstempo thresholds. The Navy and SOCOM have established perstempo thresholds in their policies and clarified which types of perstempo events apply to their thresholds. While these policies vary slightly, both the Navy and SOCOM describe in their policies the need to balance the pace of operations with the quality of life of their service members. More specifically: Navy: In 2014, the Navy issued an instruction that includes a perstempo threshold that identifies the number of days that individual Navy service members may serve away from home. The Navy’s instruction established a threshold of 220 days in a 365-day period or 400 days in a 730-day period. The Navy’s instruction also identified that the threshold applies to all deployment perstempo events—which comprise operations, exercises, unit training, temporary duty, and homestation training. Special Operations Command: In 2016, SOCOM issued a policy memorandum that establishes a perstempo threshold that identifies the number of days that individual SOCOM service members may serve away from home. The policy memorandum established a perstempo threshold of 480 days in a 730-day period. SOCOM’s policy memorandum also clarified that the threshold applies to both deployment perstempo events (e.g., operational deployments and exercises) and non-deployment perstempo events (e.g., serving as a student or trainee at a school and performing administrative, guard, or detail duties in garrison at the service member’s permanent duty station). In contrast, the Army, the Air Force, and the Marine Corps are either not enforcing or have not established a specific and measurable perstempo threshold in their policies. Officials from these services told us that they focus on managing the impact of deployments consistent with the 2013 memorandum from the Under Secretary of Defense for Personnel and Readiness, but noted that the memorandum does not set specific perstempo limits. As a result, each service has taken a slightly different approach: Army: In 2015, the Army issued a regulation that identified the number of days that a service member may spend away from home; however, Army officials told us it is not being enforced. The regulation updated the Army’s policy to include a perstempo threshold. The regulation also defined the events that could be counted toward that threshold and included a provision for the Army to manage its personnel to that threshold. However, Army headquarters officials told us that the Army is not enforcing this perstempo threshold and that the Army only added these provisions to emphasize that collecting perstempo data was a priority. According to the Army regulation, the Secretary of the Army may suspend the applicability of this perstempo program in the interest of national security, but Army headquarters officials told us that the Secretary of the Army had not suspended the perstempo program and the officials could not provide any official action that suspended the requirement. Air Force: The Air Force does not have a specific and measurable perstempo threshold in policy. An Air Force personnel instruction states that the Air Force considers service members who spend more than 120 days on temporary duty to have a high perstempo. However, Air Force headquarters officials told us that this policy does not establish a threshold for the amount of time that Air Force personnel may serve away from their homestation and that the Air Force does not require units to manage the assignments of their personnel to ensure that they do not spend more than 120 days on temporary duty. Air Force headquarters officials told us that they did not think they needed to include thresholds for perstempo in Air Force policies expressed in specific, measurable terms because the Air Force relies on unit commanders to manage the perstempo of individual service members and they believed that a perstempo threshold would affect a small number of their service members. Marine Corps: The Marine Corps also does not have a specific and measurable perstempo threshold in its policy, but its policy accounts for perstempo time in determining individual service members’ eligibility for overseas deployments, among other things. For example, Marine Corps Order 1300.8 adjusts and delays the date that service members are scheduled to deploy overseas by the amount of perstempo time accrued for those service members. The Marine Corps also issued an administrative message directing unit commanders to manage the perstempo of individual service members. However, neither of these policies establishes a specific and measurable perstempo threshold. Marine Corps officials told us that it has studied the effects of high rates of perstempo on retention and told us that these studies have not provided the Marine Corps evidence that perstempo drives retention. The approach taken by the Army, the Air Force, and the Marine Corps— to focus primarily on deployments—reflects the focus placed on deployments in DOD’s policy but this approach omits perstempo events, such as training and exercises. Such activities can take service members away from home for long periods. For example, Air Force officials told us that F-16 pilots spend considerable amounts of time participating in multiple exercises every year that require them to spend significant time away from their homestation. Similarly, a 2011 study conducted by CNA found that perstempo was very high for service members in the III Marine Expeditionary Force in Okinawa and Hawaii because of the number of exercises in which those service members participated. In particular, the study found that service members in the III Marine Expeditionary Force participate in over 70 exercises and training events per year. Additionally, relying on unit commanders to monitor the perstempo of service members without providing specific and measurable guidance leaves it to the interpretation of unit commanders to define excessive time away. Standards for Internal Control in the Federal Government state that management should define objectives in specific and measurable terms to enable it to identify risks to achieving those objectives. The standards also state that specific terms are those that are fully and clearly set forth so they can be easily understood, and measurable terms are those that allow for the assessment of performance toward achieving objectives. As we reported in 2007, shortly after the September 11, 2001, attacks, DOD shifted its focus away from collecting and maintaining perstempo data and began focusing on collecting and maintaining data to track deployments related to major operations, which does not include the full range of perstempo events. DOD continued this focus on managing deployments versus perstempo in its issuance of the 2013 memorandum. Furthermore, even as it has continued to waive the statutory perstempo thresholds and cited the effect of the high pace of operations and training on service members, DOD has not taken action to focus attention on the management of perstempo thresholds within the services and DOD. As a result, the services have taken differing approaches, with the Army, the Air Force, and the Marine Corps having no specific and measurable thresholds. Through providing specific and measurable department-wide perstempo thresholds in DOD guidance or directing the services and SOCOM to establish and follow service-specific thresholds for its service members, DOD will be better able to judge whether service members are spending too much total time away from home and, if so, whether there have been any associated effects on military readiness. DOD does not have reliable perstempo data, which limits its ability to effectively monitor perstempo across the department. In part due to the incompleteness of the perstempo data, an official within the Office of the Under Secretary of Defense for Personnel and Readiness told us that the office cannot monitor perstempo even though section 136 of title 10 makes the office responsible for doing so. For example, a December 2017 Defense Manpower Data Center analysis indicated that perstempo data are missing records for at least 145,000 individuals that deployed in fiscal years 2014-2016. In addition, officials from the Office of Cost Assessment and Program Evaluation told us that they attempted to analyze the effects of high rates of perstempo on unit readiness in 2016 but that they were unable to draw conclusions from the analysis because, among other things, the perstempo data were incomplete. Officials explained that certain events were not captured in the perstempo data consistently, such as Army rotations to a combined training center. Senior service officials also told us that the analysis had limited usefulness due to unreliable data. Although data are incomplete, our analysis of available data indicates that tens of thousands of service personnel experienced high rates of perstempo in fiscal year 2016. Because the perstempo policies vary widely, we anchored our analysis to the 220 days in a 365-day period identified in the currently waived statutory threshold. Using that benchmark, we estimate that at least 51,000 service personnel spent more than 7 months away from their homestation in fiscal year 2016 (see table 1). Moreover, we believe these numbers may be far higher because our analysis is limited by incomplete perstempo data as stated above. Additionally, our estimate likely understates the number of servicemembers as we excluded records from our analysis because they were missing an end date in the data system for the perstempo event. Further, we found that the perstempo records we analyzed for fiscal years 2012 through 2016 were also missing other information, which limits the utility of the data for users and decision makers. For example, we found that 30 percent of perstempo records for fiscal years 2012 through 2016 were missing information that identifies the service member’s occupation, 14 percent were missing information that identifies the purpose of the perstempo event, and 8 percent were missing information that identifies the category of perstempo event. Incomplete and unreliable data have presented management problems, particularly for the Navy and SOCOM as they have sought to manage the perstempo of their service members. For example, a Naval Personnel Command official who oversees the Navy’s perstempo program told us that the 18,000 Navy personnel with more than 220 perstempo days in fiscal year 2016—that we estimated using Defense Manpower Data Center data—likely significantly understates the actual number of Navy personnel with high rates of perstempo. The official stated that the Navy’s data showed that more than 31,000 Navy service members were away from home more than 220 days in fiscal year 2016—a difference of about 13,000 personnel. Officials from the Navy and Defense Manpower Data Center were unable to explain the discrepancy. Moreover, Navy officials told us that the Navy oversees perstempo by requiring subordinate commands to obtain waivers when service members exceed 220 days in a year. However, the Navy had waivers for about 6,000 personnel in 2016, or only about one-fifth of the personnel the Navy’s own data indicated were gone more than 220 days. To address this, the Navy Personnel Command official told us that the Navy plans to establish an automated system to verify that Navy service members who have exceeded the Navy’s 220-day perstempo threshold have a waiver. In addition, a SOCOM headquarters official told us that the command does not have reliable perstempo data on its service members because of limitations in the command’s information technology system. As a result, SOCOM does not currently have the ability to determine whether its units are adhering to the SOCOM perstempo threshold. The official told us that SOCOM is working to address the problem with this information technology system. We previously reported on challenges DOD has had with collecting reliable perstempo data in 1996 and 2007. While the department has made some progress, the reliability of perstempo data has remained a persistent challenge for the department. In 1996, we reported that DOD could not measure the increase in time away from home because no department-wide data system existed to track it. DOD generally agreed with our findings and recommendations and indicated that it had taken, and would continue to take, initiatives to manage perstempo. In 2007, we reported that Army and Marine Corps perstempo data were inaccurate and incomplete because of the lack of quality controls. We recommended that the Under Secretary of Defense for Personnel and Readiness provide guidance directing the Army and Marine Corps to develop quality control procedures for validating the accuracy of the perstempo data they collect and report to the Defense Manpower Data Center. The department concurred with the recommendation and issued an instruction in 2009 that required the services to report perstempo data to the Defense Manpower Data Center. However, the Under Secretary of Defense for Personnel and Readiness has not fully implemented our recommendation because the instruction did not direct the Army and Marine Corps to develop quality control procedures for validating the accuracy of their perstempo data. The Standards for Internal Control in the Federal Government state that management should use quality information to achieve its objectives and that such information should be complete and accurate. The underlying reason that perstempo data are not reliable is that DOD has not emphasized the collection of complete and reliable perstempo data. Specifically, an official from the Office of the Under Secretary of Defense for Personnel and Readiness told us that the office last reviewed perstempo data in 2012 and, at that time, determined that these data were not fully reliable. The official also told us that to address this challenge the office reiterated the requirement that the services must collect perstempo data in its 2013 memorandum, but the memorandum did not emphasize that the perstempo data collected should be complete and reliable. Without taking steps to improve the quality of its perstempo data, DOD will be limited in its ability to assess the amount of time service members are serving away from home for all perstempo events and use that information to assist them in monitoring and gauging the stress on the force. In the years since 2001, senior DOD leaders have expressed concern about the impact of a high pace of military operations and the high pace has continued for portions of the force. DOD has taken steps to limit operational deployments for individual service members, but has been less focused on the impact of total time away from home on personnel, commonly called perstempo. Total time away from home includes the training and other activities that can take service members away from home for long periods. DOD has two primary and long-standing challenges in managing perstempo: setting clear policy and gathering reliable data. First, DOD has not established a perstempo policy with specific and measurable thresholds even as it has waived a statutory requirement that sets such thresholds. In the absence of clear and specific guidance, the Navy and SOCOM have set their own thresholds. By contrast, the Army set a threshold but does not enforce it and the limits for Air Force and Marine Corps service members are unclear. Unless DOD ensures that perstempo thresholds are established and followed across the department in specific and measurable terms, DOD will be unable to judge when individual service members are spending too much time away from home. Second, perstempo data are unreliable across the department—primarily because they are incomplete—but high perstempo is affecting tens of thousands of personnel. For example, available data indicate that at least 51,000 active duty personnel spent more than 7 months per year away from home in fiscal year 2016, and the number may be considerably higher. Incomplete perstempo data are a persistent problem that continues to hamper efforts to oversee the impact of time on duty away from home on individual service members. Until DOD and the military services take steps to emphasize the collection of complete and reliable perstempo data, DOD will be limited in its ability to oversee the time its personnel are spending away from home or gauge the stress on the force. We are making two recommendations to DOD. The Secretary of Defense should ensure that the Under Secretary of Defense for Personnel and Readiness, in conjunction with the Secretaries of the Army, the Navy, and the Air Force; the Commandant of the Marine Corps; and the Commanding General of SOCOM, clarify its guidance on perstempo thresholds as long as the statutory thresholds are waived by either establishing specific and measurable department-wide perstempo thresholds in DOD policy or ensuring that the Army, the Air Force, and the Marine Corps establish and follow their own service-specific guidance on thresholds. (Recommendation 1) The Secretary of Defense should ensure that the Under Secretary of Defense for Personnel and Readiness, in conjunction with the Secretaries of the Army, the Navy, and the Air Force; the Commandant of the Marine Corps; and the Commanding General of SOCOM, take steps to emphasize the collection of complete and reliable perstempo data so that DOD, the services, and SOCOM can monitor perstempo. (Recommendation 2) We provided a draft of this report to DOD for review and comment. In written comments, DOD concurred with our two recommendations. DOD separately provided technical comments, which we incorporated as appropriate. DOD’s written comments are reprinted in their entirety in appendix I. We are sending copies of this report to the appropriate congressional committees; the Secretary of Defense; the Under Secretary of Defense for Personnel and Readiness; the Secretaries of the Air Force, the Army, and the Navy; the Commandant of the Marine Corps; and the Commanding General of SOCOM. In addition, the report is available at no charge on the GAO website at http://www.gao.gov. If you or your staff have any questions about this report, please contact me at (202) 512-3489 or pendletonj@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. GAO staff members who made key contributions to this report are listed in appendix II. John H. Pendleton, (202) 512-3489 or pendletonj@gao.gov. In addition to the contact named above, Patricia Lentini, Assistant Director; Suellen Foth; Mae Jones; James P. Klein; Amie Lesser; Ricardo Marquez; Shari Nikoo; Joshua Parr; and Michael Silver made key contributions to this report. Navy Readiness: Actions Needed to Address Persistent Maintenance, Training, and Other Challenges Affecting the Fleet. GAO-17-809T. Washington D.C.: September 19, 2017. Navy Readiness: Actions Needed to Address Persistent Maintenance, Training, and Other Challenges Facing the Fleet. GAO-17-798T. Washington, D.C.: September 7, 2017. Military Readiness: DOD’s Readiness Rebuilding Efforts May Be at Risk without a Comprehensive Plan. GAO-16-841. Washington, D.C.: September 19, 2016. Special Operations Forces: Opportunities Exist to Improve Transparency of Funding and Assess Potential to Lessen Some Deployments. GAO-15-571. Washington, D.C.: July 16, 2015. Military Personnel: DOD Lacks Reliable Perstempo Data and Needs Quality Controls to Improve Data Accuracy. GAO-07-780. Washington, D.C.: July 17, 2007. Military Readiness: A Clear Policy Is Needed to Guide Management of Frequently Deployed Units. NSIAD-96-105. Washington, D.C.: April 8, 1996.

Summary: In 1999, Congress required DOD to monitor the time that individual service members spend away from home and set a threshold to limit excessive time away. At the time, the threshold was no more than 220 days served away from home in a 365-day period. In the interest of national security, in 2001 DOD exercised a provision in the law and waived the requirement to limit time away for service members. Recently, DOD leaders have stated that the continued high pace of military operations have limited their ability to rebuild readiness. Senate Report 114-255 includes a provision for GAO to review the root causes of degraded readiness, including reviewing DOD's management of perstempo. This report assesses the extent to which DOD, the services, and SOCOM have (1) policies with specific and measurable thresholds on perstempo and (2) reliable data to monitor perstempo. GAO analyzed DOD, service, and SOCOM perstempo policies and analyzed DOD-wide perstempo data for fiscal years 2012-2016. The Department of Defense (DOD), military service, and U.S. Special Operations Command (SOCOM) policies vary in identifying specific and measurable thresholds on the total time individual service members can be away from home, known as personnel tempo or “perstempo.” DOD's policy issued in 2013 states that service members should not be deployed for longer than they are at home. However, the policy does not set thresholds for perstempo, which includes time away from home for exercises and training in addition to deployment. Service members are sometimes away from home for long periods for training, exercises, or other activities. For example, Air Force officials told GAO that F-16 pilots participate in multiple exercises every year that require them to spend significant time away from home. The Navy and SOCOM set specific and measurable perstempo thresholds in policy in 2014 and 2016, respectively. However, the other services either are not enforcing or have not established specific and measurable perstempo thresholds in their policies. DOD has maintained the waiver of statutory perstempo thresholds since 2001, and officials have cited the effect of the high pace of operations and training on service members; however, DOD has not taken action to focus attention on the management of perstempo thresholds within the services and department-wide. Unless DOD ensures that perstempo thresholds are established and followed while statutory thresholds are waived, DOD will be unable to judge whether service members are spending too much total time away from home and, if so, whether this has resulted in any associated effects on military readiness. DOD does not have reliable data to monitor perstempo because the data are incomplete. Based on available DOD-wide data, GAO estimated that for fiscal year 2016 at least 51,000 service personnel spent more than 7 months away from home. However, that number is conservative because the analysis is limited by incomplete data. Specifically: DOD analysis shows that perstempo records are missing for at least 145,000 personnel who deployed in fiscal years 2014-2016. For fiscal years 2012-2016, 30 percent of DOD's perstempo records were missing information that identifies service members' occupations, 14 percent were missing information that identifies the purpose of the perstempo events, and 8 percent were missing information that identifies the category of perstempo events. The Navy identified about 13,000 personnel who spent more than 220 days away from home in fiscal year 2016 but were not accounted for in the DOD-wide data, and DOD officials could not explain why they were missing. Without taking steps to emphasize the collection of complete and reliable perstempo data, DOD will be limited in its ability to assess the amount of time service members are serving away from home for all perstempo events and in its ability to use that information to assist in gauging the stress on the force. GAO recommends that DOD (1) clarify its policy to include specific and measurable department-wide perstempo thresholds for use while statutory thresholds are waived or ensure service-level policies are established and followed, and (2) take steps to emphasize the collection of complete and reliable perstempo data. DOD concurred with GAO's recommendations.