517000 Telecommunications (including wired, wireless, satellite, cable, & other program distribution, resellers, agents, other telecommunications, & internet service providers)
Data Processing, Web Search Portals, & Other Information Services
518210 Computing infrastructure providers, data processing, web hosting, & related services
519200 Web search portals, libraries, archives, & other info. services
Motion Picture & Sound Recording
512100 Motion picture & video industries (except video rental)
999000 Unclassified establishments (unable to classify)
How to use the IRS business code lookup
1Describe your business or type a codeFor example “long haul trucking”, or a six-digit NAICS or IRS code.
2Pick the IRS principal business codeThe six-digit code for Schedule C (Form 1040), line B, with the NAICS codes it covers.
3Check against the IRS instructionsUse the current year’s Instructions for Schedule C before you file.
Good to know
IRS business code vs. NAICS code
The IRS list is based on NAICS but shorter: one IRS code often covers several NAICS codes, so it is not always the same number.
Where you need each one
Schedule C asks for the IRS principal business code; SAM.gov and government bids use the NAICS code.
Questions
What is a business code?
The principal business or professional activity code is the six-digit code you enter on Schedule C (Form 1040), line B. The IRS uses it to classify sole proprietorships by the type of activity they are engaged in; the codes are based on NAICS.
How do I find my business code?
The IRS instructions say: select the category that best describes your primary business activity, then the activity that best identifies the principal source of your sales or receipts, and enter its six-digit code on Schedule C, line B (their example: 531210 for offices of real estate agents and brokers). The lookup above does the same search for you.
Is the IRS business code the same as my NAICS code?
Not always. The IRS list has 304 codes, and many of them cover a group of NAICS codes: 541600 covers all management, scientific and technical consulting (NAICS 541611–541690). Use the IRS code on Schedule C, and the full six-digit NAICS code for SAM.gov, government bids and SBA size standards.
What if my income is from farming?
The IRS instructions say that if your principal source of income is from farming activities, you should file Schedule F instead of Schedule C.
What code do I use if I sell online?
The IRS instructions say nonstore retailers (internet, mail-order, direct sales) should select the code for their primary line of products sold. For example, a business mainly selling prescription and nonprescription drugs uses 456110 Pharmacies & drug retailers.
What if no code fits my business?
The IRS list ends with 999000 Unclassified establishments (unable to classify). Try describing your main activity in other words first; most businesses fit one of the 303 other codes.
Source: Internal Revenue Service, Instructions for Schedule C (Form 1040) (2025), “Principal Business or Professional Activity Codes” (public domain); NAICS lines from the U.S. Census Bureau 2022 NAICS. PublicBeam is independent and not affiliated with the IRS or any agency. This is not tax advice: always check the current IRS instructions before you file.
Business Codes for “consulting” – Business Code Lookup