The Department of Commerce identifies the economic base of the country (i.e., products and services) by types of industry, such as manufacturing, construction, agricultural, service group, etc., through a coding system. This system enables the government to obtain the data it needs to analyze economic trends and similar information.
North American Industry Classification System (NAICS) Codes: NAICS codes (pronounced "nakes") are used for classifying business establishments and industries doing business with the government. You must supply at least one for your registration to be complete. If you do not know your NAICS codes, you may search on the Internet at http://www.census.gov for links to the NAICS search site. You must use six-digit NAICS Codes in your registration.
Although you have to enter only one valid code for your registration to be complete, be sure to list all codes that apply to your products and services. This could help government buying offices identify your company as one that provides needed goods or services. When entering your codes, don't get carried away by putting in a lot of different ones. Be realistic and use those NAICS that are best for you.
Effective October 1, 2002, the Small Business Administration is using the NAICS 2002 version of the codes for their size standards. They apply to all SBA programs and to all other federal government programs and actions where eligibility as a small business is a factor or a consideration.
Standard Industrial Classification (SIC) Codes: Formerly, the government had used these codes for classification of businesses and industries, but is still a mandatory field for registering in CCR. You must supply at least one valid SIC code for your registration to be complete. If you do not know your SIC codes, you may search on the Internet at http://www.osha.gov/oshstats/sicser.html. Some agency or buyer may still be using the system, and you should be aware of what your numbers are and/or how to find them. SIC codes can be four or eight digits.
You can access the SIC manual on the Internet through the Small Business Administration's home page or in hard copy through your public library. If you are using a print copy of the manual, you can find your SIC Code by looking for your industry and then going down the list to see where you fit.
Note: When you set up your company, particularly if you incorporated, chances are that it was classified with a SIC code because that's one of the things that's asked for in the incorporation papers.