NAICS code on your tax return

Every federal business tax return asks for a six digit activity code. The IRS calls it the principal business or professional activity code on Schedule C and the business activity code on corporate returns. The codes come from a chart in each form's instructions, and the IRS states that "these six-digit codes are based on the NAICS." Most of the time your IRS code and your NAICS code are the same number. Sometimes the IRS code is a grouped version of it. If you do not know your NAICS code yet, describe the business in the NAICS calculator and it returns the code.

Where the code goes on each return

Each form also asks you to describe the activity in words. Schedule C line A asks for your principal business or profession, including product or service. Form 1065 has items A and B for principal business activity and principal product or service, and the corporate forms ask for the business activity and product or service next to the code. Keep the words and the code consistent: "Residential remodeling" with 236100 reads as one business, "Residential remodeling" with 541600 does not.

The code chart is the same list across these forms, printed at the end of each set of instructions.

How the IRS list relates to NAICS

The IRS list is a six digit list derived from NAICS with its own groupings. For many industries the IRS code and the NAICS code match exactly: a beauty salon is 812112 in both. For others the IRS collapses several NAICS industries into one code ending in zeros.

The IRS groups where NAICS detail does not change much for tax statistics. NAICS splits consulting into seven industries, from 541611 general management consulting to 541690 other scientific and technical consulting. The IRS uses one code, 541600, for all of them. NAICS splits residential building into four codes by type of builder. The IRS uses 236100.

The practical rule: put the IRS code on the tax return and the full NAICS 2022 code everywhere else, including SAM.gov, SBA applications and loan applications. A lender who sees 541600 on your return and 541611 on your application sees the same business at two levels of detail.

The IRS chart follows the 2022 NAICS retail restructure. Online and other nonstore sellers pick the code for the primary product they sell. The Schedule C instructions give the example of a business selling drugs, which uses 456110, pharmacies and drug retailers. Our page on the NAICS code for an LLC has a table of retail codes for online sellers.

Common Schedule C codes and the matching NAICS codes

When the IRS code ends in 00 and NAICS has several six digit codes underneath, pick the NAICS code by the same rule as always: the activity that earns the most revenue. A sole proprietor who files 541600 and gives marketing advice is 541613 for NAICS purposes. The page on NAICS codes for consulting breaks down the full consulting group.

Choosing the right code for the return

1. Identify the activity that brings in the most revenue for this business, not for the owner personally. Each Schedule C covers one business.
2. Find the NAICS code for that activity. The calculator gives it to you from a plain description.
3. Find the IRS code in the chart at the end of the instructions. If your NAICS code appears, use it. If not, use the grouped code that starts with the same digits.
4. Use the 999000 unclassified establishments code only when nothing fits. It tells the IRS and anyone who reads your return nothing about the business.

If you run two separate businesses as a sole proprietor, each gets its own Schedule C with its own code. A business with two activities inside one entity reports one code, for the larger activity.

Where lenders read the code

Lenders ask for two to three years of business returns, and the activity code on page 1 is one of the first things an underwriter sees. They compare it with the NAICS code on your application, the description of the business and the bank statements. When all four tell the same story, the file moves. When the return says 541600 and the application says 238220, the underwriter stops and asks why.

Your NAICS code also decides which lenders see the file at all, since lenders set appetite and pricing by industry. Start an application and the AI matches the deal to lenders that fund your code.

What happens if the code is wrong

Nothing dramatic. The IRS uses activity codes to compile statistics and to compare returns within an industry, and a wrong code on its own does not trigger a penalty. You do not need to amend a past return just to change the code. Put the correct code on your next return and keep it consistent from then on.

Fix the other places the code lives at the same time: SAM.gov, state registrations, Dun and Bradstreet and your lenders. The guide on how to change your NAICS code walks through each one. If you are starting from scratch, the guide on how to find your NAICS code shows how to land on the right one the first time.