Finding the right NAICS code for your business
Updated August 6, 2026
Six digits. That's the entire length of a NAICS code, and those six digits decide whether a contracting officer's opportunity search even turns up your business, and whether you legally count as a small business for that specific contract.
NAICS stands for the North American Industry Classification System. It's a shared code list used by the Census Bureau, the IRS, and every federal contracting officer to describe what kind of work a business actually does. Quick note before we go further: zerogov.net is a privately run site, not SAM.gov and not any federal agency, so what follows is practical guidance based on our own registration experience, not official instruction. You'll pick at least one NAICS code during SAM.gov registration, and it isn't a throwaway field. It's tied directly to two things that matter a lot: whether you show up in an agency's search for a given opportunity, and what size standard applies when someone checks your small business status.
Why the code carries more weight than it looks like
Every NAICS code has its own small business size standard, set by the SBA, usually expressed as either average annual revenue or number of employees. A code with a higher revenue cap and a code with a lower employee headcount cap can apply to businesses that look nothing alike on paper. Your size status under one code tells you nothing about your status under a different one. That matters for eligibility to bid on set-asides at all, and the set-aside categories themselves (8(a), WOSB/EDWOSB, SDVOSB, HUBZone) still get built on top of that same size determination even after the 2026 FAR overhaul, which we cover in more detail in our plain-English rundown of that overhaul.
Opportunities on SAM.gov are also filtered by NAICS code. If your registration lists a code that doesn't match what you actually sell or do, you can miss solicitations that were a real fit, simply because the search never returned you as a match in the first place.
Picking a primary code that's actually accurate
Pick the code that reflects the largest share of your revenue or your core line of work, not the one that sounds most impressive and not the one under which you'd happen to have the loosest size standard. Reviewers can usually tell when a code doesn't match a company's real history, and a mismatch undercuts your credibility on evaluated factors like relevant experience.
A rough process that works for most small businesses:
- List every distinct service or product line your business actually delivers today, not ones you're hoping to grow into.
- Search each one against the official code descriptions rather than guessing from a code's short title, since two codes can sound almost identical and cover very different work.
- Rank them by revenue share. The top one becomes your primary code.
- Add the rest as secondary codes, as many as genuinely apply to what you do.
| Primary NAICS code | Secondary NAICS codes | |
|---|---|---|
| What it controls | Your default small business size status and the code most closely tied to your registration | Additional opportunities you can be matched to, without changing your primary size determination |
| How many you get | One | Several. SAM.gov allows multiple entries |
| Common mistake | Picking the code with the friendliest size standard instead of the one matching actual revenue | Listing codes for work you don't really perform, hoping to appear in more searches |
Secondary codes are worth adding generously, as long as they're honest. There's little downside to being findable under a code for work you genuinely do on the side. There's real downside to a primary code that doesn't match your business, since it's the one examiners and contracting officers tend to weigh most heavily if your size status ever gets questioned.
Where to actually look up the codes
The NAICS code list itself is maintained by the U.S. Census Bureau and is free to search. You don't need a paid lookup tool or a subscription service to find or check a code, the same way you don't need to pay anyone to register in SAM.gov itself. If you land on a site charging a fee just to search NAICS codes, close the tab. Within SAM.gov's own registration workflow there's a built in NAICS search you can use to browse and select codes directly. Cross check the code description against your actual business activity before you commit to it, and revisit your code list every so often, since your revenue mix and services can shift over time.
One honest note here: this page is independent and unofficial. Zerogov.net isn't a government site and isn't SAM.gov, we're a small business that went through registration ourselves and wrote down what we learned along the way. Nothing here replaces the actual FAR text or SBA regulations, and if your code selection is genuinely ambiguous, it's worth getting a second opinion rather than guessing.
Getting your NAICS code right is one piece of a longer registration process, and it's easy to get a step out of order or miss a required field entirely. We built a free SAM.gov registration checklist that covers the rest of that process, including exactly where NAICS selection fits into the sequence.