NAICS Codes for Government Contracting: Complete Guide

NAICS (North American Industry Classification System) codes are 6-digit numbers that classify every business by the type of work it performs. The federal government assigns a NAICS code to every contract opportunity, making it the primary way contracts are categorized and searched.

Your primary NAICS code also determines your SBA size standard — the threshold that defines whether your business qualifies as "small" for that type of work.

When a contracting officer creates a solicitation on SAM.gov, they assign a single NAICS code. This code determines which size standard applies, which set-aside programs are available, and which contractors will see the opportunity in their searches.

The top NAICS codes in federal contracting by volume include 541512 (Computer Systems Design), 541511 (Custom Programming), 541330 (Engineering), 541611 (Management Consulting), and 561210 (Facilities Support).

Most companies qualify under multiple NAICS codes. Your primary code should represent the work that generates the majority of your revenue. Secondary codes cover other services you offer.

To find the right code: search the Census Bureau NAICS lookup by keyword, review what NAICS codes appear on contracts similar to work you perform, and check what codes your competitors register under in SAM.gov.

Each NAICS code has a size standard — either a revenue cap (e.g., $34 million) or an employee count (e.g., 1,000 employees). If your business is below the threshold, you qualify as a small business for that code.

This matters because 23% of federal contract dollars are reserved for small businesses through set-aside programs. A company might be "small" under NAICS 541512 ($34M threshold) but "large" under NAICS 561210 ($47M threshold).

Choosing the right NAICS codes is a strategic decision. Consider the competitive landscape in each code — how many awards are made, who wins them, and at what price. A less crowded NAICS code with fewer competitors may offer better win rates than the obvious choice.