By Outrider Editorial Team · Updated August 20, 2026
PSC D399 was the catch-all of the old D3xx IT service series. It no longer appears in the PSC Manual. In the October 2020 restructure the government end-dated 68 IT PSCs and activated 40 replacements, retiring the entire D3xx series in favour of the tower-based DA through DK codes. Despite that, $1.84 billion moved under D399 in FY2025, because obligations recorded in a fiscal year include modifications booked against awards signed years earlier under the old code set.
Where the money sits
Computer Systems Design Services (541512) took $1.15 billion, 517110, Wired Telecommunications Carriers, took $241 million, Other Computer Related Services (541519) took $217 million, satellite telecommunications 517410 took $106 million, and 541511 took $39 million.
The PSC and NAICS split, briefly
The PSC classifies the requirement and the NAICS code classifies the vendor, and only the PSC side was restructured in 2020.
If your market research or competitive analysis is keyed on D399, you are watching a code that no new solicitation should use. Rebuild those saved searches on the live equivalents. Application work is DA01 and DA10, IT management is DF01 and DF10, networks are DG01, DG10, and DG11, security is DJ01, and genuinely mixed IT requirements now have to pick a tower.
NAICS crosswalk
Where FY2025 D399 dollars landed, by the winning vendor's registered NAICS code.
- 541512Computer Systems Design Services$1.2B
- 517110Wired Telecommunications Carriers$240.7M
- 541519Other Computer Related Services$217.4M
- 517410Satellite Telecommunications$105.9M
- 541511Custom Computer Programming Services$39.0M
FY2025 federal contract obligations, USAspending.gov
Frequently Asked
PSC D399 questions, answered.
What does PSC D399 cover?
It was the residual code for IT and telecommunications services that did not fit the other D3xx codes. The whole D3xx series was end-dated in the October 2020 PSC restructure and does not appear in the current manual.
What NAICS codes win D399 work?
Computer Systems Design Services (541512) at $1.15 billion leads FY2025, followed by Wired Telecommunications Carriers (517110) at $241 million and Other Computer Related Services (541519) at $217 million.
Why does a retired PSC still show FY2025 obligations?
Reported obligations are transaction-level and include modifications, option exercises, and de-obligations booked in FY2025 against awards signed under the earlier code set. The original PSC stays with the award.
What replaced D399?
The tower-based codes activated in 2020: DA for applications, DB for compute, DC for data center, DD for service delivery, DE for end user, DF for IT management, DG for network, DH for platform, DJ for security and compliance, and DK for storage.
Watch D399 opportunities
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