6 active solicitations·5 federal agencies·Last refreshed Jul 5, 2026
Active opportunities in NAICS 561621
Refreshed continuously from SAM.gov and partner agencies. Showing the 5 most-urgent active solicitations.
Top primes in NAICS 561621
Federal primes ranked by total obligated dollars under NAICS 561621 over the last 5 fiscal years. Source: USAspending.gov.
#1
SERCO INC7 contracts · Department of Defense
$579.9M
#2
OLGOONIK GLOBAL SECURITY, LLC.1 contract · Department of State
$397.4M
#3
GENERAL DYNAMICS MISSION SYSTEMS, INC.2 contracts · Department of Defense
$237.4M
#4
M. C. DEAN, INC.9 contracts · Department of Justice
$236.3M
Agencies buying NAICS 561621
The top federal customers historically active in NAICS 561621by obligated dollars. Match your past performance to the agency that’s most likely to write your next contract.
#1
Department of Defense60 contracts
$2.1B
#2
Department of Homeland Security18 contracts
$467.2M
#3
Department of State2 contracts
$455.0M
#4
Department of Justice6 contracts
$128.0M
Frequently asked questions
What is NAICS 561621?
NAICS 561621 is the federal industry code for Security Systems Services (except Locksmiths). The Census Bureau maintains the NAICS taxonomy; federal contracting officers use it to classify solicitations and confirm bidder eligibility.
How do I bid on federal contracts as a small business in NAICS 561621?
Register your business in SAM.gov, get a UEI, and confirm your NAICS code matches the solicitation's primary NAICS. Then write a capability statement that maps your past performance to the work in the RFP. Themis automates the matching and gives you a free AI brief for every active opportunity.
Do I need a SAM.gov registration to bid?
Yes — every federal contract award above the micro-purchase threshold requires the vendor to have an active SAM.gov registration with a Unique Entity Identifier (UEI) and the relevant NAICS codes listed on the registration.
What set-asides apply to NAICS 561621?
Common federal set-asides — Small Business (SBA), 8(a), HUBZone, SDVOSB, WOSB, EDWOSB — apply per solicitation, not per NAICS code. Each opportunity declares its own set-aside; Themis displays the eligibility class on every card so you can filter to ones you qualify for.
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