NAICS Classification & Reference Center
The NAICS Classification & Reference Center is SICCODE.com’s organized library for NAICS definitions, structure, history, FAQs, governance guidance, and code lookup tools. Use this hub to explore NAICS from the top-level hierarchy down to individual code pages—then verify selections using included/excluded activities, examples, and parent hierarchy context.
On this page
Scope and principles
SICCODE.com provides a reference layer for NAICS that emphasizes clarity, consistency, and audit-ready rationale. NAICS assignment is treated as a governed interpretation process, especially for businesses with multi-activity operations or ambiguous public descriptions.
Core principles
- Primary activity focus: classification aligns to the business’s primary activity as described and evidenced.
- Hierarchy consistency: selections respect the NAICS structure from sector to national industry.
- Explainability: decisions should be justifiable using observable business signals.
- Stability over time: avoid unnecessary churn; changes should reflect evidence or NAICS revision cycles.
What this page is not
- Not a replacement for official NAICS publications.
- Not a guarantee of eligibility for any specific program or procurement requirement.
- Not an instruction to self-select codes without validating included/excluded activities.
Evidence inputs used for NAICS assignment
NAICS classification is strongest when it is grounded in verifiable signals about what a business actually does. SICCODE.com uses a governed review approach that can incorporate multiple sources of evidence where appropriate.
Common evidence signals
- Company descriptions and activity statements (public-facing)
- Products/services offered and operational keywords
- Industry terminology and customer market positioning
- Operational context and activity mix (when available)
Reference anchoring
- NAICS hierarchy alignment (sector → subsector → industry group → industry → national industry)
- Included vs excluded activity logic on code pages
- Parent-child fit checks to reduce misclassification drift
How SICCODE.com resolves NAICS assignment decisions
Many businesses appear to match multiple NAICS codes. When ambiguity exists, SICCODE.com applies a structured decision approach designed to improve consistency.
Decision rule of thumb: prefer the code that best fits the primary revenue-generating activity and the most specific NAICS definition that matches the business’s actual operations.
Resolution workflow
- Candidate identification: identify likely codes based on business activity evidence.
- Hierarchy validation: confirm each candidate fits the correct parent structure.
- Included/excluded confirmation: verify the business’s activity is included and not explicitly excluded.
- Specificity selection: choose the most specific defensible code consistent with the evidence.
- Documentation and review: record rationale and apply expert review for edge cases when needed.
Methodology in action: examples
The examples below show how a governed, establishment-level approach resolves common ambiguity patterns that often produce inconsistent NAICS results across vendors. These are reference examples designed to illustrate decision rules and stability controls.
Example 1: Resolving multi-activity ambiguity
Multi-activity businesses are a common source of NAICS inconsistency. Keyword-only approaches often over-weight branding language (for example, “consulting”) while under-weighting the primary operational activity. The example below shows how SICCODE.com resolves ambiguity while preserving stability over time.
The case: “Solar Solutions & Consulting Group”
The business installs solar panels, offers energy efficiency consulting, and sells solar components online.
Governed resolution process
- 1) Candidate identification: identify candidates for installation, consulting services, and retail/e-commerce based on activity signals.
- 2) Primary activity determination: focus on what the business primarily does using observable evidence (service emphasis, operational keywords, and offering footprint).
- 3) Hierarchy alignment: validate that the selected code fits the correct parent structure and does not drift into adjacent industries.
- 4) Included/excluded check: confirm the primary activity is included in the selected code and not explicitly excluded into a nearby category.
- 5) Documentation: record rationale and note secondary activities to reduce churn when marketing language changes.
Outcome (what is produced)
Primary NAICS selection: NAICS 238210 (installation-focused classification)
Secondary activities recorded: consulting and online component sales noted as secondary/supporting functions.
Governance note: By documenting secondary activities, the primary NAICS code remains stable even if the company’s marketing shifts toward “consulting” or “technology” language. This reduces classification drift across vendor datasets and reporting periods.
Example 2: Resolving vertical integration (manufacturing + wholesaling/retailing)
Vertical integration occurs when a business operates across multiple stages of a supply chain, such as manufacturing, wholesaling, and retailing. Without governance, these businesses are often misclassified into Merchant Wholesalers or Retail Trade based on channel language rather than establishment activity.
The case: “Apex Industrial Sealing Corp”
The business designs and manufactures custom rubber gaskets in a factory setting. In addition, it maintains a warehouse operation that distributes both self-manufactured products and third-party industrial seals, along with a limited on-site retail counter for trade customers.
Governed resolution process
- 1) Establishment-level assessment: confirm whether manufacturing, warehousing, and retail activity operate as one integrated establishment.
- 2) Primary activity determination: determine the primary value-adding activity using observable operational evidence rather than channel terminology.
- 3) NAICS rule application: when manufacturing is significant and occurs within the same establishment as wholesaling or retailing, classification is generally anchored to Manufacturing.
- 4) Code selection: select the most specific defensible manufacturing code consistent with the activity scope and hierarchy.
- 5) Secondary activity documentation: document wholesaling/retailing as secondary distribution activities to prevent sector drift over time.
Outcome (what is produced)
Primary NAICS selection: NAICS 326291 (illustrative manufacturing-anchored example)
Secondary activities recorded: wholesale distribution and limited retail counter documented as secondary activities.
Governance note: A search for “industrial seal distributor” may surface this business. Governed interpretation anchors classification to the primary value-adding activity (manufacturing) and records downstream channels as secondary to preserve stability and avoid double-counting across sectors.
Related NAICS governance pages: NAICS Data Governance & Versioning · NAICS Accuracy Benchmarks · NAICS Classification & Reference Center
Quality checks and explainability
NAICS assignment should be consistent and explainable. Quality checks focus on reducing drift, preventing category inflation, and maintaining stable classification logic across similar businesses.
Consistency checks
- Parent/child alignment check (structural fit)
- Duplicate intent check (avoid redundant or overly broad selections)
- Outlier detection against comparable business activity profiles
Explainability outputs
- Clear “what this code covers” logic on code pages
- Included vs excluded activity clarity
- Examples and contextual notes for ambiguous terms
Use these guides when you need consistent, establishment-level decisions, clear boundaries, or defensible NAICS use in programs and compliance workflows.
Handling revisions and change cycles
NAICS is revised over time. SICCODE.com’s governance approach supports stable interpretation while incorporating revision cycles in a controlled and transparent manner.
- Revision-aware mapping: changes are evaluated for impact on code definitions and boundaries.
- Controlled updates: avoid churn unless evidence or framework revisions justify change.
- Audit-friendly tracking: preserve rationale and linkage to the NAICS hierarchy context.
FAQ
- Is SICCODE.com an official NAICS publisher?
No. SICCODE.com provides a reference layer aligned to the official NAICS framework to help users interpret and apply NAICS consistently. - Why do businesses match multiple NAICS codes?
Many organizations operate multiple activities. NAICS assignment typically reflects the primary activity, with hierarchy and included/excluded logic used to resolve ambiguity. - How do I confirm a NAICS code is the right fit?
Compare candidate codes using the code page’s coverage notes, included vs excluded activities, examples, and parent hierarchy context. - Does NAICS change over time?
Yes. NAICS revision cycles can adjust definitions and boundaries. A governed approach helps keep classifications stable and defensible across updates.