A SIC code (Standard Industrial Classification code) is a four-digit number assigned to a business that identifies what industry it operates in. Developed by the U.S. government in 1937, the system organizes the entire economy into numbered categories so that agencies, insurers, and analysts can group and compare businesses by type. Even though a newer system called NAICS has largely replaced it for statistical purposes, SIC codes are still actively used by the SEC, OSHA, and many private-sector organizations.
How the Four-Digit System Works
The SIC system is hierarchical. It starts broad and gets more specific with each digit. At the top level, the economy is divided into 11 major divisions covering areas like manufacturing, retail trade, finance, and services. Those 11 divisions break down into 83 two-digit major groups, which split further into 416 three-digit industry groups, and finally into 1,005 four-digit industry codes.
The first two digits of any SIC code identify the major group. The third digit narrows it to a specific industry group, and the fourth digit pinpoints the exact industry sector. For example, SIC codes starting with 20 fall under “Food and Kindred Products.” A code of 2080 narrows that to beverages, and 2082 specifies malt beverages. This layered structure lets analysts zoom in or out depending on how detailed they need the classification to be.
Who Still Uses SIC Codes
The SEC is the most prominent government agency that continues to rely on SIC codes. Every company that files documents through the SEC’s EDGAR database is tagged with a SIC code indicating its type of business. The SEC’s Division of Corporation Finance also uses these codes to assign review responsibility for filings. A company classified under Metal Mining (SIC 1000), for instance, would have its filings reviewed by staff in the Office of Energy & Transportation.
OSHA still maintains a searchable version of the 1987 SIC manual on its website, and workers’ compensation insurers frequently use SIC codes to assess risk and set premium rates. Businesses also use SIC codes to identify and pursue government contracts, since many federal and state procurement systems categorize opportunities by industry classification. Banks and lenders sometimes reference SIC codes during commercial loan underwriting to understand what sector a borrower operates in.
SIC Codes vs. NAICS Codes
The North American Industry Classification System (NAICS) was introduced in 1997 as a more modern replacement for SIC codes. NAICS uses six digits instead of four, which allows for finer distinctions between industries. It recognizes 1,170 industries compared to SIC’s 1,004, with 358 categories that are entirely new to NAICS. Most of those new categories, about 250, cover service-producing industries that barely existed or weren’t well represented when SIC codes were last updated in 1987.
The two systems also differ in how they group businesses. SIC codes were organized based on a mix of what a company produces and what demand it serves, which led to some inconsistencies. NAICS groups businesses strictly by the processes they use to produce goods or services. A company that manufactures frozen dinners and one that manufactures frozen desserts might end up grouped differently under SIC but together under NAICS if they use similar production processes.
NAICS was also developed jointly by the U.S., Canada, and Mexico, which makes it possible to compare industry data across all three countries. SIC codes have no equivalent international framework. The Census Bureau, Bureau of Labor Statistics, and most federal statistical agencies now use NAICS exclusively. But because the SEC, OSHA, and much of the insurance industry still reference SIC codes, most businesses need to know both.
How to Find Your SIC Code
OSHA maintains a free online search tool that lets you look up SIC codes by keyword. You type in a description of your business activity, and the tool returns matching codes from the 1987 SIC manual. You can also browse the manual’s structure by starting at the two-digit level and drilling down to three-digit and four-digit codes until you find the best match.
The SEC publishes a full SIC code list on its website, which is useful if your company files with the SEC or you want to see how publicly traded companies in your industry are classified. If you already have a NAICS code (from your tax filings or Census Bureau correspondence), several free crosswalk tools online map NAICS codes to their closest SIC equivalents.
When selecting a code, focus on the primary activity that generates the most revenue for your business. A company that both manufactures furniture and sells it at retail would typically use the manufacturing SIC code if manufacturing accounts for the larger share of revenue. Picking the right code matters because it can influence your workers’ compensation premiums, your eligibility for certain government contracts, and how regulators categorize your filings.