By Outrider Editorial Team · Updated August 20, 2026
PSC AC31 is basic research coded to the defense-related activities subfunction, the third leg of the National Defense budget function alongside DoD military and atomic energy defense. FY2025 obligations were $975 million.
A retired NAICS code holding two-thirds of it
$651 million, about 67 percent, sits under NAICS 541712, Research and Development in the Physical, Engineering, and Life Sciences (except Biotechnology). That code was superseded in the 2017 NAICS revision by the 541715 series. Physical, Engineering, and Life Sciences R&D (541715) itself takes only $172 million here. Compare AC11, the DoD military basic research code, where the current registration leads comfortably. The difference is a good proxy for contract age: AC31's money is running through older awards. Engineering services 541330 adds $80 million, 336992, Military Armored Vehicle, Tank, and Tank Component Manufacturing, adds $19 million, and 541511 adds $16 million.
PSC against NAICS, once
The PSC comes from the contracting officer and describes the purchase; the NAICS code comes from the vendor's SAM.gov profile and describes the company.
Both classification systems get revised, on different schedules, which is why a current PSC can pair with a superseded NAICS code on the same award.
NAICS crosswalk
Where FY2025 AC31 dollars landed, by the winning vendor's registered NAICS code.
- 541712Research and Development in the Physical, Engineering, and Life Sciences (except Biotechnology)$651.4M
- 541330Engineering Services$80.0M
- 541511Custom Computer Programming Services$16.2M
FY2025 federal contract obligations, USAspending.gov
Frequently Asked
PSC AC31 questions, answered.
What does PSC AC31 cover?
Basic research funded under the defense-related activities subfunction of the National Defense budget function, distinct from DoD military and atomic energy defense research.
What NAICS codes win AC31 work?
NAICS 541712 took $651 million of $975 million in FY2025, about two-thirds, with Physical, Engineering, and Life Sciences R&D (541715) at $172 million and Engineering Services (541330) at $80 million.
Why is a superseded NAICS code the largest here?
NAICS 541712 was replaced in the 2017 revision, but obligations continue against awards registered under it. A high share of retired codes usually indicates long-running contracts, not new competition.
How does AC31 differ from AC11?
Both are basic research. AC11 is the DoD military subfunction and AC31 is defense-related activities, a much smaller budget category whose R&D coding practice varies more across agencies.
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