How NAICS classifies federal work, how SBA size standards apply, and how to pick the codes that won't trap you later.
Last reviewed on May 12, 2026.
The North American Industry Classification System (NAICS) is a six-digit code used to classify business activities across the United States, Canada, and Mexico. Federal contracting uses NAICS for three jobs:
A common surprise for new contractors: a firm can be small under one solicitation and large under another, depending on which NAICS code the contracting officer assigned. A software firm at $20M in revenue is small for most computer services codes (which carry a $34M-ish receipts standard at this writing) but may be large for some specialized publishing or product codes with lower receipts standards.
The SBA publishes the authoritative size standards table at sba.gov/document/support-table-size-standards. Check the current version before relying on a number you found elsewhere; SBA periodically inflates the receipts thresholds and occasionally restructures the table.
The two main measures:
Receipts and employees are calculated for the firm plus its affiliates. Affiliation rules are technical and worth attention — common pitfalls include shared ownership across multiple entities, identity of interest among family members, and joint venture relationships outside the SBA Mentor-Protégé Program. The SBA's affiliation regulations at 13 CFR 121.103 are the authoritative source; consult counsel if your ownership is complex.
SAM.gov lets you list multiple NAICS codes, but one must be designated primary. The primary code is what filters searches by contracting officers and determines small business eligibility for several SBA programs. Selection criteria:
Three to ten codes is a common range. Fewer than three may make your SAM record too narrow for searches; more than ten is rarely meaningful because contracting officers usually filter by a single code per solicitation. Each additional code should describe a service line you can actually deliver — not a wish list. Inflated NAICS lists make your capability statement and SAM record look unfocused.
Sometimes a solicitation is issued under a NAICS code that does not seem to match the work. This is grounds for a NAICS code appeal at the SBA Office of Hearings and Appeals (OHA). Timing is short — typically 10 calendar days from the issuance of the solicitation. Successful appeals can change the size standard and either expand or restrict who can compete.
Most contractors never need to file a NAICS appeal. But knowing it exists is useful when a solicitation looks miscoded and the difference materially affects who is "small."
Every NAICS code used in federal contracting has an associated SBA size standard, but the standard is set by SBA rather than being part of the NAICS classification itself. Standards are expressed either as average annual receipts or as number of employees, depending on the industry. The same firm can therefore be small under one code and other than small under another — which is why the code a contracting officer assigns to a solicitation determines your eligibility for it.
It is the threshold below which a firm counts as a small business for that industry — typically average annual receipts over a multi-year period, or average number of employees. Fall below it and you can compete for small business set-asides under that code; exceed it and you cannot, regardless of your status under other codes. Check the current figure against SBA's official table of size standards rather than a cached copy, since the thresholds are periodically adjusted.
Six. The structure narrows from a two-digit sector through three-digit subsector, four-digit industry group, five-digit NAICS industry, to the six-digit national industry level. Federal solicitations cite the six-digit code, and it is at that level that size standards apply.
Start from the work you actually perform and can evidence with past performance, not from the codes with favorable size standards. List the codes for each distinct service line — most firms legitimately have several — and check the size standard for each. Then look at how federal buyers classify the work you want: search awarded contracts on USAspending.gov for requirements like yours and see which codes agencies assigned. If your self-classification does not match how buyers classify the work, buyers win.
Yes, and it is common. Size is determined per code, so a firm may be comfortably small under a services code with a receipts-based standard and other than small under a manufacturing code with an employee-based one. Your eligibility for any specific opportunity is judged against the code assigned to that solicitation.