Final answer:
The question asks about a policy that enables the Department of Defense to exceed appropriations for certain essentials but offers no reference to a specific act. While constitutional clauses provide Congress with military spending powers, the statement's accuracy cannot be determined without additional legislative context.
Step-by-step explanation:
The statement mentions an act that authorizes the Department of Defense to incur obligations beyond available appropriations for essential supplies within the current year, but excludes construction (MILCON) and personnel (MILPERS) costs. This question is not directly stated verbatim in law or policy; thus, determining its truth requires understanding of various legislative and constitutional principles. When considering the constitutional abilities of Congress, particularly in Sections 8 Clause 12 and 8 Clause 13, it indicates that Congress holds the powers related to raising and supporting armies and navies, setting rules for military behavior, and controls military spending with appropriations not extending beyond two years. Furthermore, Section 8 Clause 2 acknowledges Congress's power to borrow money and deficit spend, particularly for national defense.
However, for a specific act or authority related to the Department of Defense as described in the question, we would need to refer to the specific legislative text or policy guidance which is not provided here. As such, without specific reference to a named act, ascertaining the veracity of this statement is not possible based on the given information and should be researched directly in legislative texts, policies, or official statements concerning the Defense Department's fiscal authorities.