If you have ever tried to pull a targeted business list and found yourself staring at a six-digit code wondering whether it actually describes your prospect, you are not alone. NAICS codes (the North American Industry Classification System) are the modern standard for classifying businesses across Canada, the United States, and Mexico, and they show up constantly in list targeting, government data, and CRM fields. Yet a lot of marketers still find them harder to work with than they should be, especially when their existing systems or historical data were built around the older SIC code system.
This guide breaks down what NAICS codes are, how they differ from SIC codes, why the distinction still matters in 2026, and how to use NAICS classification to build a sharper B2B targeting list.
What NAICS Codes Actually Are
NAICS was introduced in 1997 to replace the aging SIC system with a classification standard shared across Canada, the US, and Mexico, making cross-border industry comparison more consistent. Instead of a four-digit code, NAICS uses up to six digits, with each additional digit narrowing the classification further.
The structure works like this: the first two digits identify the broad sector (for example, manufacturing or professional services), the next two narrow it to a subsector, the fifth digit identifies the industry group, and the sixth digit, where used, specifies the national industry in fine detail. That extra granularity is the main practical advantage NAICS has over SIC: it can distinguish between businesses that an older four-digit code would have lumped together. You can browse the full code hierarchy using our NAICS code search tool.
NAICS codes are also updated on a five-year revision cycle to reflect changes in the economy, which means a code that was accurate a few years ago may have been reclassified. Marketers building lists against NAICS should confirm they are working from a current version rather than an outdated code set.
NAICS vs. SIC: Why Both Still Show Up
Despite NAICS being the modern standard, SIC codes have not disappeared. Many commercial databases, legacy CRM fields, and older B2B marketing workflows still reference SIC codes, partly because they were embedded in systems built before NAICS existed and partly because some data vendors never fully migrated. The practical result is that a marketer building a targeting list today may need to work with both systems depending on which platform or vendor they are pulling from. If you need to look up the older system, our SIC code search covers the full four-digit structure.
This creates a specific, common mistake: mixing SIC and NAICS codes incorrectly when a platform only supports one system, or assuming a SIC code and its “equivalent” NAICS code describe exactly the same set of businesses. They often do not. A broad SIC category can map to several more specific NAICS codes, and several older SIC categories can collapse into a single NAICS code, depending on how the underlying business classification changed between the two systems. Getting this conversion wrong is one of the more common ways a supposedly targeted list ends up including businesses that do not actually match the intended segment.
Why This Matters More for Cross-Border Campaigns
Because NAICS is shared across Canada, the US, and Mexico, it is the more reliable classification system for marketers running campaigns on both sides of the border. A Canadian company targeting US manufacturers, or a US company targeting Canadian professional services firms, benefits from NAICS precisely because the classification logic is consistent across both countries rather than relying on country-specific SIC interpretations.
For a Canadian list broker’s clients specifically, this matters in a very concrete way: pulling a list by NAICS code rather than SIC ensures the same targeting logic applies whether the campaign is running in Toronto, Chicago, or both. It also reduces the risk of under- or over-targeting that comes from trying to translate SIC codes across a border where they were never quite designed to match one-to-one. For a full walkthrough of a cross-border campaign built this way, see our guide to building a manufacturing industry marketing campaign targeting decision makers in Canada and the US.
How to Use NAICS Codes to Sharpen a Targeting List
Start with the sector level to confirm you are in the right broad category, then move down through the subsector and industry group levels to see how the six-digit codes branch out. It is common to discover, once you look at the full hierarchy, that your actual target audience sits across two or three adjacent NAICS codes rather than a single one you had originally assumed was correct.
From there, cross-reference the specific six-digit codes against your existing customer base if you have one. Pulling the NAICS codes of your best current customers and using those as a starting point, rather than guessing from a general industry description, is one of the more reliable ways to identify adjacent codes worth including in a prospecting list.
Finally, treat NAICS as one filter among several, not the only one. Company size, geography, and title still matter enormously for whether a NAICS-classified business is actually a good fit for your outreach. A six-digit NAICS code narrows the industry, but it does not tell you whether the specific company is the right size or has the right decision-maker for your offer. This is also where a custom-built list outperforms a generic database pull, a difference we cover in detail in Custom Lists vs. Off-the-Shelf Databases.
Common Questions Marketers Run Into
Can I just use the NAICS code that seems closest to my industry description? You can, but it is worth checking the full hierarchy first. Businesses are sometimes classified by their primary registered activity rather than the activity most visible to an outside observer, which means the code that seems intuitively correct is not always the one under which a target company is actually filed.
Do I need to update codes I have been using for years? If your list or CRM was built against an older NAICS revision, it is worth confirming the codes still map to the same industries. The five-year revision cycle occasionally reclassifies or splits categories, and a code that was accurate in one revision may describe a slightly different set of businesses in the next.
Is NAICS enough on its own for B2B targeting? Generally not by itself. NAICS narrows the industry classification, but a complete targeting brief still needs company size, geographic scope, and the specific titles you want to reach layered on top. If any of the terminology in this process is unfamiliar, our business lists glossary defines the terms list brokers use when scoping a targeting brief.
A Worked Example of the Hierarchy in Practice
It helps to walk through how the NAICS hierarchy actually narrows in practice. Start at the two-digit sector level, which might identify a business broadly as being in manufacturing. The four-digit level narrows this to a specific subsector, such as machinery manufacturing. The five-digit industry group narrows further still, and the full six-digit code identifies the specific national industry, distinguishing, for example, between a company that manufactures general-purpose machinery and one that manufactures specialized machinery for a single narrow application.
This matters practically because two companies that look similar from the outside, both described loosely as “machinery manufacturers,” can sit under entirely different six-digit codes once you look closely, with correspondingly different buying patterns, budget cycles, and pain points. Marketers who stop at the two- or four-digit level are often targeting a much broader and less relevant audience than they realize. You can see how granular the branching gets by exploring a sector in our NAICS code search, or by browsing an example segment like our manufacturing companies list.
How NAICS Codes Interact With Company Size Data
NAICS classification tells you what a business does, but it says nothing about how big that business is or how many locations it operates. Pairing NAICS codes with employee count, revenue range, or number of establishments is what turns an industry classification into an actionable targeting filter. A six-digit NAICS code covering a narrow manufacturing niche might include both a five-person operation and a five-hundred-person enterprise, and those two companies almost certainly need very different messaging, pricing conversations, and decision-maker outreach. This is exactly why segments like a small business list exist as a distinct product rather than a byproduct of industry classification alone.
This is one of the more overlooked steps in NAICS-based list building: treating the classification as sufficient on its own rather than as one filter to be combined with size, geography, and title criteria before the list is considered finished.
Getting the Classification Right the First Time
Working through NAICS hierarchies, cross-referencing SIC equivalents, and confirming you are on the current revision is exactly the kind of detail work that turns a rough industry guess into a precisely targeted list. It is also the kind of work a list broker handles as a matter of course, rather than something a marketing team needs to solve from scratch for every new campaign.
Prospects Influential builds custom business lists using accurate NAICS and SIC classification matched to your specific criteria, industry, geography, company size, and title, so you are not left reconciling code systems on your own. Lists are typically prepared within one to two business days of confirming your criteria, and once delivered, they can be used across as many campaigns as you need with no cap on usage, whether that campaign runs through direct mail, telemarketing, or opt-in email.
To see how classification-based targeting works in practice, take a look at our Business List SIC Codes guide for a companion breakdown of the older system, visit our business lists hub to discuss a custom NAICS-based list for your next campaign, or request a quote directly.
