A six-digit number decides whether you count as a small business on a given federal contract. That number is your NAICS code, and most owners treat it as a formality they click through during SAM registration. It isn't. The wrong code, or the wrong assumption about which code applies, can knock you out of a set-aside you were built to win.
Here's how NAICS actually works in federal contracting, who picks the code on each opportunity, and why your own list of codes matters less than you'd think.
What a NAICS code does in federal contractingNAICS stands for the North American Industry Classification System. It's the shared vocabulary the federal government uses to describe what an industry does. Code 541512 is computer systems design. Code 236220 is commercial building construction. Code 561720 is janitorial services. There are over a thousand of them, six digits each, organized from broad sector down to specific industry.
The system is maintained by the Census Bureau and revised every five years, in years ending in 2 and 7. The 2022 edition is the current standard, and the next revision is targeted for 2027. When the revision lands, some codes get merged, split, or renumbered, so the code you use this year may shift. It's worth knowing the cycle exists so a renumbering doesn't catch you off guard.
In federal contracting, NAICS does two jobs. It tells agencies what you do, so they can find you during market research. And it carries the SBA size standard, which is the part that decides whether you're small.
The agency assigns the code, not youThis is the piece most first-timers get backwards. You do not choose the NAICS code on a contract. The contracting officer does.
Under SBA's rules at 13 CFR 121.402, the contracting officer must designate a single NAICS code for each solicitation, the one that best describes the principal purpose of what's being bought. That designation goes on the solicitation, and it sets the size standard for that specific opportunity. Every business bidding is measured against the same standard, the one attached to the code the CO picked.
So when you read a solicitation, look for the NAICS code in the notice. That code tells you the size standard you'll be judged against on this contract. If you think the CO picked the wrong code, there's a formal way to challenge it: an appeal to the SBA Office of Hearings and Appeals, filed within a tight window after the solicitation is issued. That's a real lever, but it's a narrow one, used mostly when a misclassification changes who qualifies as small.
What your own codes do is different. They make you findable and they describe your business. They don't override the code on a given solicitation.
Choosing your primary and additional codes in SAMWhen you register in SAM.gov, you list the NAICS codes your business operates under. You pick one as your primary code, and you can add as many additional codes as genuinely apply.
Your primary code is the single code that best describes your main line of business. It's the one that shows up first in your profile and the one buyers tend to associate with you. Choose it honestly. If most of your revenue comes from IT staffing, that's your primary, even if you'd love to win construction work someday.
Your additional codes broaden the range of opportunities where you'll surface in a contracting officer's market research. Add the codes that reflect work you actually perform or are credibly positioned to perform. Don't pad the list with codes you have no business in. A CO who pulls you up under a code you can't deliver on remembers it, and your Dynamic Small Business Search profile is built from these same codes, so an inflated list reads as noise.
A practical rule: your codes should match the work you'd put on a capability statement. If you couldn't write a credible past-performance line under a code, it probably doesn't belong on your list yet.
Why one code can make you "other than small"Here's where the size standard earns its keep. Every NAICS code has an SBA size standard attached to it, and the standards are not uniform. The SBA publishes them in a table tied to each code (13 CFR 121.201), and they come in two flavors.
Receipts-based standards apply to most service, construction, and retail industries. The threshold is a dollar figure, and the SBA measures you against it using your average annual receipts over your five most recently completed fiscal years.
Employee-based standards apply to manufacturing, mining, and some utilities. The threshold is a headcount, and the SBA uses the average number of employees over your most recently completed 12 pay periods.
The standards vary widely from code to code. One industry's small-business ceiling might be a few million in receipts; a neighboring industry's might be many times that, or measured in hundreds of employees instead of dollars. So the same company can be comfortably small under one of its NAICS codes and "other than small" under another.
That matters because the code on the solicitation, the one the CO assigned, is the one that decides your status for that contract. If a buyer issues an opportunity under a code whose size standard you exceed, you don't qualify as small for it, even if you're small under every other code you carry. This is why two businesses of identical size can have opposite small-business status on the same bid: they're being measured against different codes.
If you're sizing up which set-aside programs you can realistically pursue, the size standard is the gate that sits underneath all of them. Our guide to federal set-asides covers how 8(a), HUBZone, WOSB, and SDVOSB layer on top of that small-business determination.
How to look up a code and its size standardYou can look up codes and standards by hand on the Census NAICS site and the SBA size standards table, cross-referencing the two. It works, but it's slow, and the two sources don't sit in one place.
Our NAICS lookup tool does it in one step. Search by keyword or by code, find the codes that fit your business, and see the SBA size standard attached to each one, receipts or employees, side by side. Use it before you register so you walk into SAM knowing your primary code, your additional codes, and exactly where you stand on size for each.
Look up your codes and size standards in the NAICS tool.
Updating your codes in SAMYour codes aren't locked in at registration. As your business shifts into new lines of work, or drops old ones, update your NAICS list in SAM so your profile and your DSBS listing stay accurate.
Two moments are worth a deliberate review. First, your annual SAM renewal, when you're already in the record and reps and certs are open anyway. Second, the next NAICS revision in 2027, when some codes will change and you'll want to confirm yours carried over correctly. Outside those, update whenever your actual work changes enough that a contracting officer searching your old codes would miss you, or find you under work you no longer do.
If you haven't registered yet, get your codes straight first, then file. Our walkthrough on how to register on SAM.gov lays out the full order, with NAICS as one of the things to settle before you log in.
