561621 — Security Systems Services (except Locksmiths)
Description
This U.S. industry comprises establishments primarily engaged in (1) selling security alarm systems, such as burglar and fire alarms, along with installation, repair, or monitoring services or (2) remote monitoring of electronic security alarm systems (as defined in the official U.S. Census Bureau 2022 NAICS Manual).
Overview Facts
Legacy SIC Concordance
Trace the historical mapping chain from the 1987 Standard Industrial Classification (SIC) to the modern 2022 NAICS code format.
- SIC 7382 - Security Systems Services (via SIC1987:7382→NAICS1997:561621→2002:561621→2007:561621→2012:561621→2017:561621→2022:561621)
Suggested Product Service Codes (Advisory)
The following Product Service Codes (PSCs) are advisory suggestions aligned with this NAICS code. Note: NAICS and PSC codes map to different dimensions of procurement (industry vs. product/service). There is no official binding 1:1 crosswalk.
- PSC 6350 — Miscellaneous Alarm, Signal, and Security Detection Systems
Source: DoD DPCAP PSC Selection Tool (Ingested: 2026-06-29)
Frequently Asked Questions (FAQ)
Is NAICS code 561621 valid in 2022? ▾
Yes, 561621 is a valid 6-digit 2022 NAICS national industry code representing 'Security Systems Services (except Locksmiths)' under Sector 56 in the official classification index.
What is the SBA size standard for NAICS code 561621? ▾
The Small Business Administration (SBA) has established a small business size standard of $25,000,000 for NAICS code 561621 (Security Systems Services (except Locksmiths)), calculated based on receipts.
What is the legacy SIC equivalent for NAICS 561621? ▾
According to official Census Bureau concordance tables, NAICS code 561621 (Security Systems Services (except Locksmiths)) maps to legacy 1987 Standard Industrial Classification (SIC) codes: 7382 - Security Systems Services.
Related Pages & Tools
Further regulatory reference links for NAICS code 561621:
- Sector 56 Directory Hub — List of related industries in the Administrative and Support and Waste Management and Remediation Services sector.
- SIC ↔ NAICS Crosswalk Tool — Look up mappings between legacy SIC codes and modern classifications.
- NAICS 561621 to SIC Crosswalk — Bidirectional mapping to legacy SIC codes (Security Systems Services (except Locksmiths)).
- SBA Size Standards Guide — Complete rules and averaging periods for small business classifications.
- Calculating Annual Receipts Guide — Detailed worked example of revenue calculation rules.
- IRS Principal Business Activity Guide — How NAICS codes map to corporate and entity tax filings.