Under 10 U.S.C. §115(a) Congress sets the maximum size (i.e., end-strength) of the active and reserve components of the Armed Forces annually, typically in a National Defense Authorization Act (NDAA). Congress is also responsible for appropriating funds for the pay and benefits of these personnel.
End-strength specifically refers to the actual number of personnel in a branch on the last day of the fiscal year (i.e., September 30). The enacted end-strength figures in the Servicemember Quality of Life Improvement and National Defense Authorization Act for Fiscal Year 2025 (FY2025 NDAA; P.L. 118-159) are for September 30, 2025. Congress also periodically sets minimum end-strength levels for the Armed Forces, which may be identical to or lower than the authorized end-strength. While Congress authorizes minimum and maximum end-strengths, each military service manages its force, through recruiting and retention efforts, to achieve an actual end-strength.
Typically, this actual end-strength falls within the congressionally authorized minimum and maximum end-strengths. However, there are circumstances in which the actual end-strength may fall outside the authorized range. For example, under 10 U.S.C. §115(f)(3), the Secretary of Defense (who is now using "Secretary of War" as a "secondary title" under Executive Order 14347 dated September 5, 2025) may—after determining "such action is in the national interest"—increase the end-strength of any of the services above the authorized end-strength by up to 3%. Recruiting and retention shortfalls may cause one or more of the services to fall below their minimum authorized strength.
The reserve component provides "trained units and qualified persons available for active duty in the armed forces, in time of war or national emergency, and at such other times as the national security may require, to fill the needs of the armed forces whenever more units and persons are needed than are in the regular components." (This provision is codified at 10. U.S.C. §10102).
Under 10 U.S.C. §113a(b)(2), the Secretary of Defense is required to submit end-strength requests for the reserve component in an annual request to Congress. Congress is not bound by these requests, but from FY2001 to FY2025 authorized end-strengths similar to the Pentagon's requested numbers.
The reserve component consists of the federal reserve forces of the Army, Navy, Air Force, Marine Corps, and Coast Guard, plus the Army National Guard (ARNG) and Air National Guard (ANG). The Space Force does not have a reserve component. It is a single-component armed service with personnel serving in an inactive or active-duty status (10 U.S.C. §20001). The National Guard (ANG and ARNG) may be mobilized under federal or state authority and performs homeland security missions that may include responding to civil unrest and natural disasters and guarding domestic airspace.
Congress has varied authorized end-strengths over time in response to factors such as national security priorities, budget constraints, and recruitment challenges.
In the report (S.Rept. 118-58) accompanying the Senate-passed National Defense Authorization Act for Fiscal Year 2024 (FY2024 NDAA, S. 2226 §411), the committee stated that it chose to recommend lower end-strengths than requested for the Selected Reserve because "legislating unreachable end strength numbers would set the military services up for failure" by "encouraging quantity over quality in recruiting." It remains unclear whether incremental reductions in previous years may have stemmed in part from this concern.
| Figure 1 . Selected Reserve Component Authorized End-Strength FY2001-FY2025 Request |
Figure is interactive in HTML report version.
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Source: CRS analysis of Congress for FY2001–FY2024 data. FY2025 data from President's Budget Request.
Note: Coast Guard reserve personnel, part of the Department of Homeland Security, are not shown.
|
Service |
Change from Enacted FY2024-FY2025 |
|||
|
Army National Guard |
325,000 |
325,000 |
325,000 |
0 |
|
Army Reserve |
174,800 |
175,800 |
175,800 |
+1,000 |
|
Navy Reserve |
57,200 |
57,700 |
57,700 |
+500 |
|
Marine Corps Reserve |
32,000 |
32,500 |
32,500 |
+500 |
|
Air National Guard |
105,000 |
107,700 |
108,300 |
+3,300 |
|
Air Force Reserve |
69,600 |
67,000 |
67,000 |
-2,600 |
|
Total |
763,600 |
765,700 |
766,300 |
+2,700 |
Source: Congress.gov, Office of the Under Secretary of Defense (Comptroller).
On December 23, 2024, former President Biden signed into law the FY2025 NDAA. This law largely enacted the end-strengths requested by the Secretary of Defense, though it authorized 600 more personnel than requested for the ANG. (See Table 1).
S.Rept. 118-188, the report accompanying the SASC-reported version of an FY2025 NDAA (S. 4638), explained that the increase in the ANG end-strength is intended "to offset any reductions that may occur as a result of transferring units and personnel from the Air National Guard to the Space Force." Section 514 of the enacted NDAA authorizes the transfer of 578 ANG billets from the ANG to the single-component Space Force, less than the authorized ANG end-strength increase.
Congress may set policy priorities independent of the executive branch through legislation and oversight. As Congress considers a FY2026 NDAA, it may consider whether or not to adjust end-strengths to achieve its defense policy objectives.
Congress may decide to adjust reserve component end-strengths for a range of reasons:
Congress may also choose to approve end-strengths that closely or exactly align with DOD requests.