NAICS Code for Security Services
Federal security services contracting is a large, specialized market driven by the need for armed and unarmed guards at federal installations, clearance-gated security services, and physical security infrastructure. DHS, DoD, GSA, and the courts are major buyers. NAICS selection for security firms is more constrained than most sectors because the guard services NAICS is narrowly defined.
Primary NAICS codes for security services
561612: Security Guards and Patrol Services ($29M size standard) The core security NAICS. Armed and unarmed guard services, patrol, access control at federal facilities. Most dedicated security firms primary here.
561621: Security Systems Services (except Locksmiths) ($25M size standard) For firms installing and monitoring security systems: surveillance, alarms, access control systems, CCTV. Different from physical guard services.
561611: Investigation Services ($25M size standard) For background investigation, due diligence investigations, corporate investigations. Distinct from guard services but often associated with security firms.
561210: Facilities Support Services ($47M size standard) For bundled contracts where security guard services are part of a broader facilities contract.
Secondary NAICS codes to consider
541690: Other Scientific and Technical Consulting Services ($19M) For security consulting — physical security assessments, risk assessments, policy development.
541330: Engineering Services ($25.5M) For security engineering and design work on physical security infrastructure.
541512: Computer Systems Design Services ($34M) For cybersecurity firms adjacent to physical security.
Which code should be your primary
The defining question is guards vs. systems vs. consulting.
Guard services firms (armed or unarmed posts at federal facilities) primary under 561612. High-volume NAICS, steady federal demand, straightforward competition dynamics.
Security systems firms (installing surveillance, access control, alarms) primary under 561621. Smaller competition pool, requires technical certifications and often contractor licenses by state.
Investigation services firms primary under 561611. Narrow NAICS, specific customer base (typically personnel security and background investigations for cleared contracts).
Bundled firms that provide guards as part of a broader facilities contract primary under 561210 when guards aren't the dominant service, or under 561612 when they are.
Cleared personnel consideration
Many federal security contracts require cleared guards (Secret, Top Secret, TS/SCI). If your guards hold active clearances, your competitive position is meaningfully stronger because the pool of cleared security firms is much smaller than the pool of all security firms. Document clearance levels prominently in your capability statement and DSBS profile.
Personnel security work at federal installations often requires the firm itself to hold a Facility Clearance (FCL) sponsored by a federal customer. Getting an FCL takes 6-12 months. Plan accordingly if you're pursuing cleared contracts.
Size standard considerations
561612 ($29M) and 561621 ($25M) are mid-range size standards. Security firms often grow steadily via recurring guard contracts and can approach size thresholds without realizing — guard contracts are labor-intensive and revenue tracks headcount closely.
The jump to 561210 ($47M) is significant for firms that can credibly bundle guards with other facilities services. A security-primary firm that bundles janitorial and maintenance may be able to classify under 561210 and extend small-business status.
Federal demand snapshot
DHS Federal Protective Service (FPS) is the largest federal security guard buyer. FPS contracts armed and unarmed guard services at federal buildings nationwide, typically via multi-year IDIQ vehicles.
DoD installations contract security guard services for base access control, physical security patrols, and specialized facility protection.
GSA procures security for managed federal buildings.
US Marshals Service, USPS, TSA all contract security services at specific facilities and operations.
Department of State, DoE contract specialized cleared security services for sensitive facilities.
SDVOSB set-asides in security services are common — DoD and DHS both prioritize veteran-owned firms for guard contracts given the natural fit between military experience and security operations. HUBZone preference applies in security contracts at HUBZone-located installations.
Next steps
Use the NAICS recommender to validate your code selection. For cleared-personnel positioning and size-standard strategy, see the NAICS code finder guide.