SIC Classification Methodology
This page explains how SICCODE.com assigns and validates SIC (Standard Industrial Classification) codes using a structured, reference-first methodology. The approach emphasizes definition fit, evidence-based decisioning, and controlled interpretation to produce consistent, defensible SIC assignments.
On this page
Methodology principles
Definition-first approach
SIC assignments align to what the SIC definition covers (not just keywords).
Primary activity focus
When multiple activities exist, the SIC selection reflects the primary operational activity.
Interpretability
Decisions should be explainable using observable signals about business activity.
Stability
Avoid unnecessary churn over time; change only when evidence justifies a correction.
Evidence inputs used for SIC
- Company descriptions and activity statements (public-facing)
- Products and services offered
- Operational keywords and industry terminology
- Business positioning (manufacturing vs service, wholesale vs retail, B2B vs B2C)
- Comparable business profiles for repeatability checks
Assignment workflow
Decision rule of thumb: prefer the SIC code that best fits the primary operational activity and the most specific definitional fit supported by evidence.
Related references: SIC Code Lookup Directory · Structure of SIC Codes · SIC vs NAICS
- Identify candidates: derive likely SIC codes from activity signals.
- Definition fit check: verify each candidate matches the SIC scope.
- Neighbor comparison: compare adjacent or commonly confused SIC codes.
- Select most specific: choose the most specific defensible code.
- Document rationale: retain the decision logic for explainability.
- Expert review: escalate edge cases to expert review when needed.
Quality checks
Keyword dependence check
Prevents SIC selections based only on matching terms without definition validation.
Over-broad defaulting check
Avoid broad codes used to reduce uncertainty; prioritize definitional specificity.
Neighbor-code comparison
Reduces adjacent-industry drift and improves precision.
Repeatability check
Improves consistency across similar business profiles.
Legacy stability rules
- Stability-first: don’t change a SIC assignment without evidence-based justification.
- Comparability: preserve consistent coding so longitudinal analysis remains meaningful.
- Crosswalk awareness: when NAICS is also required, use conversion guidance to reduce mismatch.
Related tool: SIC to NAICS Conversion
Frequently asked questions
- How is this different from keyword matching?
Keyword-only approaches ignore definition fit and context. This methodology uses multiple evidence inputs and structured checks. - Is SICCODE.com an official SIC publisher?
SICCODE.com provides a governed reference layer to help interpret and apply SIC codes consistently; it does not replace official publications or program requirements. - How do I find the right SIC code?
Use the directory to identify candidates, then confirm definitional fit and compare adjacent codes: SIC Code Lookup Directory.