NAICS vs SIC: What's the Difference?

Two Systems, One Purpose

Both NAICS and SIC are industry classification systems used to categorize businesses by their primary economic activity. SIC (Standard Industrial Classification) was developed in the 1930s, while NAICS (North American Industry Classification System) replaced it in 1997. Despite NAICS being the modern standard, SIC codes remain in use in many legacy systems, insurance platforms, and regulatory databases.

Key Differences

Structure: SIC uses a 4-digit code, while NAICS uses up to 6 digits — providing much more granular classification. Coverage: NAICS includes hundreds of industries that didn't exist when SIC was created, especially in technology, services, and information sectors. Geography: NAICS covers the US, Canada, and Mexico, while SIC was US-only. Updates: NAICS is revised every 5 years (last: 2022); SIC was last updated in 1987.

When to Use SIC vs NAICS

Use NAICS for: tax filings, Census Bureau reporting, government contracts, and any modern business classification need. Use SIC for: legacy insurance systems, SEC filings (which still require SIC codes), OSHA reporting, and any system that hasn't migrated to NAICS yet. In practice, many organizations need both — which is why SIC-to-NAICS crosswalk tools are essential.

Converting Between SIC and NAICS

The relationship between SIC and NAICS is not always one-to-one. A single SIC code may map to multiple NAICS codes, and vice versa. This is because NAICS reorganized the entire classification structure, creating new categories and splitting others. Use the trueNAICS crosswalk converter to find the NAICS equivalent of any SIC code.

Frequently Asked Questions