Are SIC Codes Obsolete? Why SIC Codes Are Still Used Today
SIC and NAICS coexist in real-world datasets. NAICS is the modern, official standard used for most U.S. government statistical reporting and is updated to reflect new industries. SIC remains common in legacy records, commercial databases, and organizational systems where historical continuity and long-running data models still rely on SIC fields.
Many professionals see SIC codes in filings, data products, or internal systems and assume SIC must still be “official” everywhere—or that SIC is obsolete because NAICS exists. In practice, the two systems often appear side-by-side because they solve different needs: NAICS supports modern statistical classification and revisions, while SIC supports continuity across older datasets and commercial environments that still store SIC-based fields.
The Coexistence of SIC and NAICS
NAICS was introduced in the late 1990s to modernize economic statistics and improve comparability across the United States, Canada, and Mexico. It is widely used in modern government reporting and many standards-based datasets.
SIC codes, however, remain deeply embedded in long-running databases and historical records. Many companies and data providers still maintain SIC fields because their internal data models, legacy reporting, and time-series benchmarking were built around SIC and still require continuity.
SIC and NAICS: Two Different Lenses
SIC (Historical & Commercial Baseline)
SIC is a legacy U.S. classification framework commonly anchored to the government-era 4-digit structure (often associated with the 1987 SIC Manual). It persists because it remains a stable baseline for historical comparability and because many commercial datasets and internal enterprise systems still store SIC-based fields.
In practice, SIC appears in legacy datasets, older research series, and commercial/provider databases where continuity matters and where extended SIC-style segmentation may be used for targeting or analytics.
NAICS (Modern Statistical Standard)
NAICS is the modern, official industry classification system used for most current government statistical reporting. It is designed to reflect how the modern economy works and is updated periodically to incorporate emerging industries and evolving production structures.
Because NAICS provides an official 6-digit structure and an active revision cycle, many modern data teams use NAICS as their primary “current-state” standard for CRM, analytics, data science, and reporting.
Official SIC vs. Extended SIC (Commercial Segmentation)
4-Digit SIC Codes (Official Baseline)
The official SIC structure is defined at the four-digit level. These codes remain a stable baseline for historical comparability and legacy classification. When people refer to “official SIC,” they typically mean the 4-digit SIC definitions from the government-era framework.
Extended SIC Codes (Vendor-Defined)
Many commercial datasets expand SIC-style classification beyond four digits (often shown as 6–8 digits) to add segmentation and represent narrower niches. These extensions are maintained by private providers and can be useful for targeting, analytics, and internal categorization—within the context of the provider’s taxonomy.
Governance note: Extended SIC codes are not part of the official government SIC standard. Definitions vary by provider, so best practice is to document the taxonomy owner/source used in your dataset.
Why Extended SIC Codes Are Used
Extended SIC codes can add finer segmentation for commercial list building, niche targeting, competitive analysis, and certain marketing workflows. They typically preserve the official 4-digit SIC as the anchor and append additional digits to define narrower subcategories within a dataset.
Example (illustrative):
4-Digit (Baseline): SIC 7371 — Computer Programming Services
Extended (Commercial): SIC 7371-02 — Custom Software Development
Extended (Commercial): SIC 7371-03 — Web Design Services
While these map back to the same 4-digit SIC anchor, extended codes may distinguish between materially different services depending on the provider’s taxonomy.
Why NAICS Is Preferred for Modern Data
NAICS is actively revised to reflect changes in the modern economy. In the U.S., NAICS updates have occurred on a regular cycle (for example, 2017 and 2022), helping the standard incorporate evolving industries and new production models over time.
This active maintenance is one reason many modern CRM, analytics, and data science teams standardize on NAICS as their primary current-state code: it provides an official 6-digit structure, supports standards-based reporting, and reduces ambiguity when aligning with government-published definitions.
For the current official standard and industry definitions, see the 2022 NAICS Directory.
SIC and NAICS Cross-Walks
Many organizations store both SIC and NAICS codes side-by-side. This is often best practice because mappings between the two systems are not always one-to-one. A single SIC code may map to multiple NAICS codes depending on business activity details and classification rules.
Keeping both values can reduce conversion ambiguity and preserve flexibility for reporting, segmentation, and longitudinal analytics—especially when your datasets span long time horizons.
Practical Use Today
Where SIC commonly appears
- Legacy enterprise databases and long-running reporting systems
- Commercial data providers and business intelligence datasets
- Historical research series and longitudinal benchmarking
- Marketing segmentation workflows that still rely on SIC fields
If you need documented context for why SIC still appears in government systems and archives, see: What Government Agencies Still Use SIC Codes?
Where NAICS is commonly preferred
- Modern government statistical reporting and standards-based datasets
- Current-state analytics requiring an official 6-digit structure
- Data science and CRM standardization for modern industry definitions
- Cross-border comparability within North America (U.S./Canada/Mexico)
Explore NAICS definitions and structure via the 2022 NAICS Directory.
System Selection Framework
| Feature | Standard Industrial Classification (SIC) | North American Industry Classification System (NAICS) |
|---|---|---|
| Primary strength | Historical continuity & legacy alignment; common in commercial/provider databases | Modern economic reality & standards-based logic; official 6-digit structure |
| Granularity | Official baseline at 4 digits (with optional vendor-defined extensions) | Official structure through 6 digits |
| Revision cycle | Stable/static (final major government update 1987) | Actively revised (e.g., 2017, 2022) to reflect evolving industries |
| Common best fit | Legacy database alignment, longitudinal research, certain commercial segmentation | Modern government reporting, emerging industries, current-state analytics and CRM standards |
Bottom Line
A neutral way to view the two systems is as complementary standards that are often stored together: NAICS is the modern official standard for most current reporting, while SIC remains operationally important because it persists in historical records, commercial datasets, and enterprise databases designed around SIC fields. Understanding both reduces confusion and improves consistency across reporting, analytics, and data integration workflows.
Rule of Thumb: Choose NAICS when you need modern, standards-based definitions (especially at 6-digit) and alignment with current government statistical reporting. Choose SIC when you need historical continuity, legacy dataset alignment, or comparability with systems and providers that still store SIC fields. Many organizations keep both to support crosswalks and long-horizon analytics.