The Cost of Supporting Military Bases

The Department of Defense (DoD) operates hundreds of bases that support the daily operations of units in the Air Force, Army, Marine Corps, and Navy, providing services such as housing, utilities, and grounds maintenance, much as might be found in a town or city. In 2016, $25 billion—about 4 percent of DoD’s budget— was allocated to the costs of such services, called base operations support (BOS). The costs of providing such support vary between bases, and the factors that affect those costs are not clearly understood. In this report, CBO explores certain characteristics of bases, such as their size, geographic location, and the mission of the units they serve, and uses statistical methods to assess the relationship between those characteristics and BOS costs.

What Data Did CBO Use to Analyze the Cost of Base Operations Support?

CBO assembled 2016 data on more than 200 bases (about 90 percent of active-duty bases) in all four services. The characteristics CBO measured include the number of full-time DoD employees at a base, its building space, and its land area. Other characteristics CBO considered include the base’s location (in the United States or overseas), the branch of service running it, the primary mission of the units it hosts, whether it hosts a significant number of transient personnel, the local climate, and the local cost of living.

What Did CBO Find?

After analyzing all of the characteristics it identified, CBO found five that were clearly connected to a base’s BOS costs: its size, primary mission, branch of service, location, and the climate extremes that it experiences (including precipitation and temperature). Of the five characteristics, the one most strongly related to BOS costs is size, in terms of both the number of employees and the amount of building space a base has. CBO found that, with other characteristics unchanged, the increase in BOS costs associated with an increase in population was smaller at larger bases than at smaller bases. For example, the average BOS costs associated with adding an employee at extremely large bases (25,000 or more employees) were $1,000; the corresponding increase in BOS costs at very small bases (5,000 or fewer employees) was $14,000. CBO also found that adding 1,000 square feet of building space was, on average, associated with an increase of about $4,000 in annual BOS costs, regardless of a base’s size.

CBO’s results could be used to anticipate how BOS costs would change if units were relocated between bases, new units were added, or existing units were disbanded. Because CBO’s analysis suggests that BOS costs would increase less if units were added to large bases rather than to smaller ones, relocating units from smaller bases to larger ones would reduce overall BOS costs in many cases. Conversely, relocating units from larger bases to smaller ones would generally increase those costs, all other things being equal. (Creating a new unit and adding it to any base would, of course, increase overall BOS costs.)

What Are Some Limitations of CBO’s Analysis?

CBO’s analysis did not account for all base characteristics that were potentially relevant because sufficient data for some characteristics were not available or were difficult to measure. The omitted characteristics include the number of family members on the base; the age of buildings and other infrastructure; the number and type of BOS services; the intensity of operations (intensity is higher, for example, when units are mobilizing for deployment); the portion of building space used for family housing (the cost to operate and maintain family housing is funded through a separate appropriation); and the quality or standard of BOS services (higher standards are expected to cost more).

CBO’s analysis is based on the level of BOS services that bases provide today. CBO did not address whether the current level of services is optimal for ensuring readiness (the ability of service members to perform their mission) or retention (their continuation in military service). It is possible that BOS services enhance readiness by contributing to unit training or retention of personnel. A base with higher BOS costs may thus make a greater contribution to a unit’s readiness than a base with lower BOS costs. However, to CBO’s knowledge the link between the level of BOS services offered and the readiness of a unit has not been measured.