NAICS Codes Explained: Find the Right Codes for Government Contracts (2026)

What Are NAICS Codes?

NAICS stands for the North American Industry Classification System. It's a standardized numbering system used by the United States, Canada, and Mexico to classify business establishments by their primary type of economic activity. Think of it as the government's way of categorizing what every business does — from almond farming (111920) to software publishing (511210) to janitorial services (561720).

NAICS codes are 6-digit numbers organized in a hierarchical structure:

• First 2 digits: Economic sector (e.g., 54 = Professional, Scientific, and Technical Services)
• First 3 digits: Subsector (e.g., 541 = Professional, Scientific, and Technical Services)
• First 4 digits: Industry group (e.g., 5415 = Computer Systems Design and Related Services)
• First 5 digits: Industry (e.g., 54151 = Computer Systems Design and Related Services)
• All 6 digits: National industry (e.g., 541512 = Computer Systems Design Services)

The system is maintained by the U.S. Census Bureau and is updated every five years (the most recent revision was in 2022). There are over 1,000 unique 6-digit NAICS codes covering every type of business activity in the economy.

Why NAICS Codes Matter for Government Contracting

In government contracting, NAICS codes serve three critical functions:

1. Contract Classification

When a federal agency posts a contract opportunity on SAM.gov, they assign it a primary NAICS code. This code determines which category of business the agency is looking for. If you're an IT firm and the contract is posted under a construction NAICS code, that contract isn't meant for you — regardless of what the description says.

2. Small Business Size Standards

The SBA assigns a size standard to each NAICS code that determines the maximum revenue or employee count to qualify as a "small business" for that type of work. Size standards vary significantly. Under NAICS 541512 (Computer Systems Design), a small business can have up to $34 million in average annual revenue. Under NAICS 236220 (Commercial Building Construction), the threshold is $45 million. Under NAICS 511210 (Software Publishing), it's 1,250 employees.

This matters because set-aside contracts — reserved exclusively for small businesses — use the NAICS code's size standard to determine eligibility. You might be "small" under one NAICS code and "large" under another.

3. Opportunity Discovery

When you search for contracts on SAM.gov or through any contract alert tool, NAICS codes are the primary filter. Your SAM.gov registration lists the NAICS codes you're capable of performing. Smart matching tools (including GovConToday) use these codes to find opportunities that align with what your business actually does — as opposed to keyword searches that match on stray word occurrences.

How to Find Your NAICS Codes

The official NAICS lookup tool is at census.gov/naics. You can search by keyword to find codes that match your business activities. Here's a practical process:

1. Start with your primary service or product. What does your business do most of the time? If you're a software development firm, search for "software" or "computer programming" on the NAICS lookup site.
2. Review the results carefully. Read the full description of each code, not just the title. The description specifies what's included and, crucially, what's excluded. NAICS 541511 (Custom Computer Programming Services) covers writing code to client specifications. NAICS 541512 (Computer Systems Design Services) covers designing and integrating hardware and software systems. They sound similar but describe different work.
3. Add adjacent codes. Most businesses do more than one thing. A cybersecurity firm might use 541512 (Computer Systems Design), 541519 (Other Computer Related Services), and 561621 (Security Systems Services). Listing these adjacent codes expands your opportunity pool.
4. Check the size standards. For each code you select, look up the SBA size standard at sba.gov/size-standards. Make sure you qualify as a small business under each one.
5. Look at what similar companies use. On SAM.gov, you can look up other businesses in your industry and see which NAICS codes they've registered under. This is a useful sanity check.

Common NAICS Code Mistakes

After working with hundreds of small business government contractors, here are the mistakes we see most often:

Mistake 1: Using Only One NAICS Code

Many businesses register with a single NAICS code, usually the one that most obviously describes their primary work. But government agencies don't always classify opportunities the way you'd expect. An agency might post an "IT help desk" contract under 541512 (Computer Systems Design) or under 561320 (Temporary Help Services) depending on how they structure the requirement. If you're only watching one code, you miss the other.

Most successful small contractors register with 3-8 NAICS codes that cover their primary capabilities and adjacent work they can perform.

Mistake 2: Going Too Broad

The opposite problem: registering under 15-20 NAICS codes to "cast a wider net." This backfires because you'll receive alerts for work you can't actually perform, and contracting officers who review your SAM.gov profile may question your credibility. If you're an IT firm also registered under food service and construction codes, it raises red flags.

Stick to codes where you have genuine capability and past performance (or could credibly perform the work).

Mistake 3: Ignoring Size Standards

Remember, size standards vary by NAICS code. A $30 million IT firm is "small" under 541512 (Computer Systems Design, $34M threshold) but might not be under a different code with a lower threshold. If you register under a code where you exceed the size standard, you can't compete for small business set-asides under that code — and misrepresenting your size is a serious compliance issue.

Mistake 4: Never Updating Your Codes

NAICS codes are updated every five years, and your business evolves too. If you registered on SAM.gov three years ago and haven't reviewed your codes since, you might be missing new codes that better describe your current capabilities — or clinging to codes for work you no longer do. Review your NAICS codes at least once a year, ideally when you renew your SAM.gov registration.

Using Multiple NAICS Codes to Cast a Wider (Smart) Net

The most effective strategy is to select a focused set of NAICS codes that represent your real capabilities, then use those codes as the foundation for automated opportunity matching.

For example, a managed IT services company might register under:

• 541512 — Computer Systems Design Services (their core work)
• 541511 — Custom Computer Programming Services (when they build custom tools for clients)
• 541513 — Computer Facilities Management Services (for managed hosting contracts)
• 541519 — Other Computer Related Services (catch-all for IT work that doesn't fit elsewhere)
• 518210 — Computing Infrastructure Providers, Data Processing, Web Hosting (for cloud-related contracts)

These five codes create a comprehensive net that captures IT contracts across different categorizations — without straying into unrelated territory.

How GovConToday Uses NAICS Codes for Matching

When you sign up for GovConToday, the first thing we ask for is your NAICS codes. These codes become the foundation of your match profile. Every morning, we pull new opportunities from SAM.gov and match them against your codes — combined with your set-aside preferences and target states — to build your personalized contract dashboard.

You can use unlimited NAICS codes to cover all your capabilities, whether you're a solo consultant or a firm working across multiple service lines. Start with a 14-day free trial, then $19/mo for Pro.

The key difference between GovConToday and raw SAM.gov searching is context. When we surface an opportunity, we tell you which of your NAICS codes it matched, whether it's set aside for your certification type, and when the deadline is. You don't have to click through and read the full solicitation just to figure out if it's relevant. The matching is done for you.

What Does NAICS Code Mean?

NAICS stands for the North American Industry Classification System — a standardized framework that assigns a 6-digit number to every type of business activity in the United States, Canada, and Mexico. The system was introduced in 1997 to replace the older Standard Industrial Classification (SIC) system, and it is maintained by the U.S. Census Bureau with revisions every five years.

In practical terms, a NAICS code tells the government what your business does. When you register on SAM.gov, you select the NAICS codes that describe your capabilities. When a federal agency posts a contract opportunity, they assign it a NAICS code that describes the type of work they need. The match between your codes and the contract's code is how government contracting discovery works — it is the fundamental building block of every opportunity search, every set-aside determination, and every size standard calculation. If you do nothing else right in government contracting, get your NAICS codes right.

Can a Company Have More Than One NAICS Code?

Yes — and in most cases, you should. When you register on SAM.gov, you select one primary NAICS code (the code that best represents your main line of business) and as many secondary codes as are relevant to your other capabilities. There is no limit on the number of codes you can list.

Using multiple NAICS codes matters because government agencies don't always classify contracts the way you'd expect. An agency might post an IT help desk contract under 541512 (Computer Systems Design), 541519 (Other Computer Related Services), or even 561320 (Temporary Help Services), depending on how the contracting officer structures the requirement. If you only track one code, you'll miss opportunities that land under adjacent codes.

The sweet spot for most small government contractors is 3-8 NAICS codes. Fewer than that and you risk missing relevant contracts. More than about 10-12 and you start looking unfocused — contracting officers who review your SAM.gov profile may question whether you actually have depth in any of those areas. Stick to codes where you have genuine capability or credible past performance.

NAICS Codes for Government Contracting

In government contracting, NAICS codes serve a fundamentally different purpose than they do in the private sector. In commercial business, your industry classification is mostly a tax and census formality. In federal contracting, your NAICS codes directly determine three things: which contracts you can find, which size standards apply to your business, and which set-aside opportunities you're eligible for.

Every solicitation on SAM.gov is tagged with a primary NAICS code. This code determines the SBA size standard for that contract — meaning your eligibility as a "small business" can change from one contract to the next depending on the code the agency chose. A $30 million IT firm is "small" under 541512 ($34M threshold) but would exceed the threshold under some consulting codes. This per-contract determination is why understanding NAICS codes is not optional — it's the gateway to the entire small business contracting ecosystem.

If you're just getting started with federal contracts, our guide to finding government contracts for small businesses walks through the full process from SAM.gov registration through your first bid.

Common NAICS Codes for Small Government Contractors

The table below lists the most frequently used NAICS codes among small business government contractors, along with their current SBA size standards. These cover the industries where the federal government spends the most with small firms — IT, consulting, construction, facilities, security, and professional services.

For IT-specific NAICS guidance, see our guide to government IT contracts, which covers the 5415xx codes in detail. For size standard thresholds by industry, see our SBA size standards guide.

Construction Company Industry Classification

Construction is one of the largest categories of federal contracting, and the NAICS codes for construction are organized differently than service industries. Construction codes fall in the 23xxxx range and are divided into three main subsectors: building construction (236), heavy and civil engineering construction (237), and specialty trade contractors (238).

A general contractor building federal facilities would typically register under 236220 (Commercial and Institutional Building Construction), which covers offices, hospitals, schools, and government buildings. The SBA size standard for this code is $45 million in average annual revenue — one of the higher thresholds, reflecting the capital-intensive nature of the work.

Specialty contractors should look at the 238 subsector. Electrical contractors use 238210 ($19M), plumbing and HVAC contractors use 238220 ($19M), and painting contractors use 238320 ($19M). If your firm does both general contracting and specialty work, register under multiple codes — the government frequently posts the same type of work under different codes depending on the scope. A roofing repair project might appear under 238160 (Roofing Contractors) or under 236220 if it's part of a larger building renovation. Track both to avoid missing relevant solicitations.

Janitorial Services Industry Classification

Janitorial and custodial services have their own dedicated NAICS code: 561720 (Janitorial Services). This code covers building cleaning, office cleaning, floor waxing, and general custodial work. The SBA size standard is $22 million in average annual revenue.

Federal agencies are major buyers of janitorial services — the Department of Defense, the General Services Administration, and the Veterans Affairs department all award hundreds of janitorial contracts annually. Many of these are set aside for small businesses, and a significant number flow through the AbilityOne program (which serves nonprofit agencies employing people who are blind or have significant disabilities).

If your company provides janitorial services, you should also consider adjacent codes: 561710 (Exterminating and Pest Control Services), 561790 (Other Services to Buildings and Dwellings), and 561210 (Facilities Support Services, which covers combined facility management). Registering under 561210 in addition to 561720 captures bundled contracts where janitorial is one component of a larger facilities management requirement. For guidance on which set-aside programs apply to your firm, see our set-aside guide.

What Is the Best Government NAICS Tool?

The official NAICS lookup tool is the U.S. Census Bureau's search at census.gov/naics. It lets you search by keyword and browse the full NAICS hierarchy. This is the authoritative source for code definitions and descriptions, and it's free. Use it first to identify the codes that match your business.

Once you have your codes, the question becomes: how do you use them to actually find contracts? SAM.gov lets you filter opportunities by NAICS code, but the search interface is designed for data publishing, not opportunity discovery. You can set up SAM.gov email alerts, but they're keyword-based and generate significant noise.

Tools like GovConToday take a different approach: you enter your NAICS codes once, and the system matches new SAM.gov opportunities against those codes every day, delivering a scored matches on your dashboard. Instead of searching for contracts, the contracts come to you — filtered by your NAICS codes, set-aside certifications, and target states. For a detailed comparison of available tools, see our SAM.gov vs. contract search tools comparison.

Key Takeaways

• NAICS codes are the government's standard for classifying business activities. Every contract opportunity is tagged with at least one NAICS code.
• Use the Census Bureau lookup at census.gov/naics to find your codes. Read the full descriptions, not just the titles.
• Yes, you can (and should) register with multiple NAICS codes — 3-8 codes that cover your real capabilities is the sweet spot.
• Check size standards for each code to make sure you qualify as a small business under each one.
• Review and update your NAICS codes at least once a year as your business evolves.
• NAICS-based matching (like GovConToday) is more precise than keyword-based searching because it starts from what your business does, not from a word that might appear in any context.