NAICS vs. SIC Codes Explained
Two systems, one confusing overlap. Here's why you still see "SIC code" on some forms, and why it's not what you actually need in 2026.
The short version
SIC (Standard Industrial Classification) is the older system. NAICS (North American Industry Classification System) replaced it in 1997. If you're filling out anything current — an EIN application, an LLC formation, a tax return — you want NAICS. SIC mostly survives in a few legacy corners of government and finance.
Why two systems exist at all
SIC was built in the 1930s to track industrial output across the U.S. economy. It worked fine for decades, but by the 1990s it was straining under an economy SIC was never designed for — service businesses, tech, and eventually the digital and gig economy didn't map cleanly onto categories built around manufacturing and industry.
NAICS was developed jointly by the U.S., Canada, and Mexico specifically to fix that, and to let all three countries compare economic data using shared categories. It's also updated every five years, so new kinds of business — app-based delivery, e-commerce, digital services — get their own accurate category instead of getting jammed into something built for a different era.
Where each one actually shows up today
| Use case | System used |
|---|---|
| EIN application (Form SS-4) | NAICS |
| Schedule C (Form 1040) | NAICS |
| State LLC / business registration | NAICS |
| SBA loans & size standards | NAICS |
| SEC public company filings | SIC (still required) |
| Older legacy databases & some insurance underwriting systems | Sometimes SIC |
The SEC is really the one place SIC hangs on for a specific reason — it's baked into their EDGAR filing system and hasn't been replaced. If you're not filing with the SEC, you'll almost never need a SIC code on purpose.
The structural difference
SIC codes are four digits. NAICS codes are six. That extra length isn't padding — it's precision. NAICS can describe a much narrower, more specific slice of business activity, which matters more today than it did in the SIC era simply because there are more distinct kinds of businesses to describe.
This is also why the two systems don't line up one-to-one. A single four-digit SIC code sometimes maps to several different six-digit NAICS codes, because NAICS split what used to be one broad category into multiple specific ones.
If a form doesn't say which one it wants
Assume NAICS. It's the current federal standard, and it's what the IRS, most state filing systems, and SBA programs default to in 2026. This holds true whether you're a rideshare driver setting up your first EIN, a 24-year-old launching an LLC for freelance work, or someone starting a consulting business after retiring — the paperwork doesn't distinguish based on how long you've been working, only on what the form is actually asking for.
Old habits die hard on this one — some accountants, insurance agents, and even a few state systems still say "SIC code" out of habit when they mean NAICS. If in doubt, ask which system specifically, or just default to looking up your NAICS code, since that covers the vast majority of real-world paperwork.
Find your code
Skip the crosswalk guesswork — search directly by keyword or industry and get the current 2022 NAICS code that matches your business.
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