NAICS is the federal classification system for industries, jointly maintained by the U.S., Canada, and Mexico. Every business activity has a six-digit NAICS code, and the SBA assigns a small business size standard to each code — measured either in average annual revenue or in employee count, depending on the industry. For 541512 (Computer Systems Design Services), the size standard is set in revenue; for 561730 (Landscaping Services), it is set in employees.
Federal contracts are assigned a primary NAICS code by the contracting officer, and the size standard for that code determines small business eligibility. A firm may qualify as a small business under one NAICS but not under another, depending on its revenue or workforce profile. The SBA reviews size standards on a five-year cycle and updates them as industry conditions change. Size standard revisions can move firms in and out of small business eligibility overnight, so monitoring upcoming SBA reviews matters for long-range capture planning.
For small contractors, the NAICS strategy is more nuanced than picking the codes that match current revenue. Firms should hold themselves out as small under all NAICS codes where they can credibly compete, register all relevant codes in SAM.gov, and watch upcoming size standard reviews for codes where they may lose eligibility. Pursuit decisions live and die on the contract's primary NAICS — knowing which NAICS the agency is likely to use is a capture intelligence question, not a registration one.