NAICS codes are one of those things in government contracting that seem simple but can quietly cost you thousands of dollars in missed opportunities. Pick the wrong codes and you won't show up in searches. Pick codes with the wrong size standards and you might not qualify as a small business. Get them right and you'll see contracts you never knew existed.

What NAICS Codes Are (and Why They Matter)

NAICS stands for North American Industry Classification System. It's a standardized six-digit code system that classifies businesses by the type of work they do. Every industry gets a code — from soybean farming (111110) to software publishing (511210).

In government contracting, NAICS codes serve three critical functions:

  1. Contract categorization. When a contracting officer posts an opportunity on SAM.gov, they assign a NAICS code. This determines which industry the contract falls under.
  2. Small business size standards. The SBA defines "small business" differently for each NAICS code. For some codes, small means fewer than 500 employees. For others, it means annual revenue under $16.5 million. For construction, it might be $45 million. Your NAICS code literally determines whether you qualify as small.
  3. Search and matching. When you search for contracts on SAM.gov or any contract alert tool, NAICS codes are the primary filter. If your profile lists the wrong codes, you won't find the right contracts.

How to Find Your NAICS Codes

Start with the NAICS Search Tool

Go to census.gov/naics and use the search tool. Type in keywords that describe what your business does — "IT consulting," "janitorial services," "engineering" — and look at the results. You'll typically find 3-5 codes that could apply to your business.

Look at What Your Competitors Use

Search for businesses similar to yours on SAM.gov's entity search. Look at what NAICS codes they've listed. If three of your competitors all list 541512 (Computer Systems Design Services), that's a strong signal you should too.

Check Past Contract Awards

Search FPDS.gov or USASpending.gov for contracts similar to what you'd bid on. Look at the NAICS codes assigned to those contracts. This tells you which codes contracting officers actually use for your type of work — which is more important than what the NAICS manual says.

Talk to Your APEX Accelerator

Your local APEX Accelerator (formerly PTAC) counselor has helped hundreds of businesses pick NAICS codes. They know the common mistakes and can review your selections. This is free — use it.

Top NAICS Codes by Federal Spending

Some NAICS codes have dramatically more federal spending than others. If your business could reasonably qualify under a high-spending code, that's where the opportunity is.

Information Technology

  • 541512 — Computer Systems Design Services: One of the highest-spending NAICS codes in the federal government. Covers IT system design, integration, and management. Size standard: $34 million annual revenue.
  • 541519 — Other Computer Related Services: Catches IT work that doesn't fit neatly into other categories. Cloud services, data processing, IT support. Size standard: $34 million.
  • 541511 — Custom Computer Programming Services: Software development, custom coding, application development. Size standard: $34 million.

Construction

  • 236220 — Commercial and Institutional Building Construction: Building federal facilities, offices, military structures. Size standard: $45 million.
  • 237310 — Highway, Street, and Bridge Construction: Infrastructure projects. Size standard: $45 million.

Professional Services

  • 541611 — Administrative Management and General Management Consulting: The catch-all for consulting. Covers management consulting, organizational planning, and advisory. Size standard: $24.5 million.
  • 541618 — Other Management Consulting Services: Environmental consulting, HR consulting, and other specialized advisory. Size standard: $19.5 million.
  • 541330 — Engineering Services: Design engineering, systems engineering, and technical consulting. Size standard: $25.5 million.

Facilities and Support

  • 561210 — Facilities Support Services: Base operations, facility management. Size standard: $47 million.
  • 561720 — Janitorial Services: Building cleaning and maintenance. Size standard: $22 million.

How Many NAICS Codes Should You List?

In your SAM.gov profile, you can list as many NAICS codes as legitimately apply to your business. Most small businesses should list 5-10 codes.

  • Too few (1-2): You're invisible to opportunities that match your capabilities but use a different code.
  • Too many (20+): You look unfocused, and you might accidentally list codes with size standards that disqualify you as a small business.
  • Sweet spot (5-10): Cover your core capabilities and adjacent work areas without diluting your profile.

Your primary NAICS code is especially important. This is the code that represents the majority of your revenue and is used for your overall small business size determination. Choose your primary code carefully.

Common Mistakes That Cost You Contracts

Mistake 1: Only Listing Your Primary Code

If you're an IT company that lists only 541512, you'll miss contracts posted under 541519, 541511, 541611, and 518210. Contracting officers don't always use the code you'd expect. Cast a wider net.

Mistake 2: Ignoring Size Standard Implications

Each NAICS code has its own size standard. If your company has $20 million in annual revenue, you're "small" under 541512 (size standard: $34M) but not under a code with a $16.5M threshold. Before adding a NAICS code, check its size standard at sba.gov/size-standards.

Mistake 3: Copying Competitors Without Thinking

Just because a competitor lists a NAICS code doesn't mean you should. They might have capabilities you don't, or they might have made their own mistakes. Use competitor research as input, but verify each code against what you actually do.

Mistake 4: Never Updating Your Codes

NAICS codes get revised periodically (the last major revision was 2022). New codes are added, old ones are merged. More importantly, your business evolves. If you added new service lines in the past two years, update your SAM.gov profile. Review your NAICS codes at least once a year when you renew your SAM.gov registration.

Mistake 5: Not Matching Codes to Contract Searches

Your SAM.gov profile codes and your contract search codes should overlap but don't have to be identical. When searching for opportunities, include related codes that contracting officers might use — even if they're not in your profile. You can always add a code to your profile before you bid.

NAICS Codes and Set-Asides

When a contract is set aside for small businesses, the NAICS code assigned to that contract determines the size standard. This means the same company could be "small" for one contract and "large" for another, depending on the NAICS code the contracting officer chose.

This is why it's critical to understand size standards for each of your NAICS codes. If you're close to a size threshold, you might strategically pursue contracts under codes where you clearly qualify as small and avoid codes where you're borderline.

What to Do Right Now

  1. Audit your current NAICS codes. Log into SAM.gov and review what you've listed. Are there gaps? Codes that no longer fit?
  2. Check size standards. For each code, verify you qualify as a small business. Remove any codes where you exceed the threshold (unless you're not pursuing set-asides).
  3. Research contract activity. Use FPDS.gov to see which NAICS codes get the most contract dollars in your industry. Add high-activity codes that legitimately apply to your business.
  4. Set up alerts by NAICS code. Whether you use SAM.gov or a tool like GovContract Alerts, make sure your alert filters include all your relevant NAICS codes — not just your primary one.
  5. Review annually. Put it on your calendar alongside your SAM.gov renewal.

Your NAICS codes are the foundation of your government contracting search strategy. Getting them right isn't glamorous, but it's the difference between seeing 10 relevant opportunities a week and seeing 2. Take the time to get them right — and check out our guide to contract search tools to make the most of them.