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NAICS & SIC Classification Authority
Find the correct NAICS or SIC code using governed definitions, inclusions/exclusions, and crosswalk guidance.
Established 1998
Long-standing authority in SIC & NAICS classification standards
Full Taxonomy Depth
Documentation for official and supplemental industry levels
Maintained & Versioned
Reviewed through governed standards and revision cycles
Search the Industry Classification Reference
Search by activity (e.g., “coffee shop”) or code (e.g., 541330).
Maintained reference · Establishment-level classification · Governance standards
Not sure what to search? Learn what NAICS codes are or browse by industry.
Or browse by system: NAICS Directory · SIC Directory
Select a Reference Path
Access the level of documentation required for your classification, research, or reporting workflow.
NAICS Taxonomy
Drill down through official NAICS sectors and subsectors to access primary code definitions, inclusions, exclusions, and boundary documentation.
Explore NAICS Directory →SIC Taxonomy
Navigate the SIC structure from divisions through industry groups to locate detailed industry definitions and supplemental extended codes.
Explore SIC Directory →Cross-System Mapping
Analyze the structural relationships between NAICS and SIC to support cross-system reporting, historical comparisons, and data normalization.
View Mapping Logic →Governance & Methodology
Review the protocols and revision cycles that define SICCODE.com’s citable standards, classification governance, and documentation maintenance.
Enter Authority & Trust Hub →The Unit of Classification
Classification follows the Establishment Principle, assigning codes based on specific operational activities rather than broad corporate or brand identities.
Industry classification applies to the establishment or operating unit. A single parent organization that spans multiple economic activities requires distinct codes for each unit to preserve data integrity, comparability, and reporting accuracy.
Documentation & standards overview
Below is supporting context that helps teams apply NAICS and SIC consistently across compliance, research, reporting, and analytics.
If you already know what you need, use the search above or open a directory path to drill down by sector and code.
The Role of Standardized Industry Classification
Industry classification provides the structural foundation for economic research, regulatory reporting, and enterprise data systems. A precise NAICS or SIC code assignment enables interoperability across institutions while preserving long-term analytical accuracy.
Regulatory & Institutional Compliance
Supports high-stakes filings such as tax reporting, insurance registration, government programs, and census-aligned disclosures where classification accuracy is required.
Economic Research & Longitudinal Analysis
Enables market segmentation, trend analysis, and benchmarking across time using stable, standardized industry definitions.
Supply Chain & Data Normalization
Standardizes vendor and supplier categorization across disparate systems to improve procurement transparency, risk assessment, and reporting consistency.
AI & Advanced Analytics Interoperability
Provides structured, establishment-level industry labels that support model training, dataset alignment, and industry-specific analytical workflows.
New to classification? Start with What is a NAICS Code? and What is a SIC Code?. For common questions, see the NAICS Code FAQ.
Classification standards in active use
Governed NAICS and SIC documentation is maintained for reporting, research, and cross-system normalization workflows.
Applied dataset lineage
Applied datasets are derived using governed definitions and documented mapping logic.
Cross-system continuity
SIC↔NAICS mapping logic supports historical comparison and modern reporting alignment.
Maintenance discipline
Documentation is reviewed and updated through governed standards and revision cycles.
Taxonomy Hierarchies & Structural Depth
Both systems move from broad sectors to establishment-level activities. The difference is structural: NAICS uses six official digits, while SIC uses four.
NAICS Hierarchy (Structural Depth)
- Sector (2-digit)
- Subsector (3-digit)
- Industry Group (4-digit)
- Industry (5-digit)
- National Industry (6-digit)
- Extended / supplemental level (8-digit)
Methodological note: Official NAICS standards conclude at six digits. SICCODE.com maintains supplemental eight-digit levels to support applied datasets and advanced analytical workflows.
Extended levels are supplemental refinements and are not part of the official government-issued NAICS standard.
SIC Hierarchy (Structural Depth)
- Division (range)
- Major Group (2-digit)
- Industry Group (3-digit)
- Industry (4-digit)
- Extended / supplemental level (6-digit)
Methodological note: Official SIC standards conclude at four digits. SICCODE.com maintains supplemental six-digit levels for applied research and operational datasets.
Extended levels are supplemental refinements and are not part of the official government-issued SIC standard.
Browse Primary Industry Sectors
Navigate the U.S. economy through top-level industry groupings. Select a primary sector to begin a structured drill-down into subsectors, industry groups, and individual establishment-level codes.
Browse shortcuts
Browse NAICS sectors Expand
Industry Classification Utilities
Deploy these specialized tools to synchronize disparate datasets, validate legacy classifications, and align establishment-level data with current North American standards.
SIC to NAICS Crosswalk Engine
Convert legacy SIC codes into the current NAICS standard for federal reporting and modern database alignment.
Access SIC → NAICS Crosswalk →NAICS to SIC Reverse Mapping
Translate modern NAICS codes back to SIC for longitudinal studies and systems requiring backward compatibility.
Access NAICS → SIC Tool →NAICS Code FAQ & Knowledge Base
Resolve common questions regarding establishment definitions, primary activity selection, and NAICS revision updates.
Consult NAICS FAQ →Classification Research Center
Access cross-system crosswalks, validation benchmarks, and standards-aligned classification workflows.
Enter Research Suite →Operational Application & Data Services
Institutional support: For enterprises requiring bespoke data mapping, bulk establishment records, or institutional classification support, consult our Applied Data Services & Use Cases.
Targeted business intelligence
Focus: Strategic sourcing & list generation
Construct high-precision datasets using NAICS/SIC, geography, revenue filters, and structural attributes.
Launch List Builder →Data methodology & structural overview
Focus: Transparency & data integrity
Examine database architecture, update frequencies, and the logic used to maintain applied establishment records.
Access Data Methodology →Professional Application & Feedback
Researchers and enterprise teams use SICCODE.com to validate codes, standardize datasets, and reconcile classification decisions.
“SICCODE.com has been instrumental in our sales and marketing architecture, providing the precise industry targeting required to reach the correct customers and maintain data integrity.”
Institutional user feedback (summary displayed on siccode.com)