Schedule C Business Code for Construction Trades (2025)

Updated October 23, 2026. Quick answer: The 2025 IRS chart lists 236100 for residential building construction and a separate 238 row for each specialty trade, from roofing to plumbing. The code goes on line B of Schedule C beside your line A description. A neighboring row such as 236200 or 561790 can read closer to your work, depending on the principal source of your receipts.

Rows the chart lists for construction work

The chart lists residential building construction as one row and then gives the specialty trades a row each. Because the chart is organised by activity rather than by the word on a business card, the tables below group the rows by the kind of work.

Whole-building work

Foundations, frames and the building shell

Mechanical and electrical trades

Interior finishing trades

Site work and everything else

How Schedule C asks for the trade

Line A asks for a description of the work: “Describe the business or professional activity that provided your principal source of income reported on line 1.” Line B asks for the code: “Enter on line B the six-digit code from the Principal Business or Professional Activity Codes chart” The code goes in the box on line B, beside the description.

For a roofer, an electrician or a tile setter, line A is a short plain-language description of the work and the customer, and line B is whichever row of the tables above matches. An example of the kind of description, not IRS wording: installing roofs on homes for homeowners. Another, in the same spirit: wiring new houses for a builder.

When a nearby construction row reads closer

Several rows sit close to the specialty trades on the chart. Their wording is the best guide to how far each one reaches.

Residential building construction is “Residential building construction” while “Nonresidential building construction” is the nonresidential row. The heavy and civil rows (“Highway, street, & bridge construction” and “Other heavy & civil engineering construction”) name roads, bridges and engineering projects rather than the finishing or mechanical trades. The row for “Other services to buildings & dwellings” is a services row, and its wording is about buildings and dwellings after they stand rather than about putting them up.

The chart’s rule has two steps: “Select the category that best describes your primary business activity”, and then “Then select the activity that best identifies the principal source of your sales or receipts”.

Two trades, one trade, or no trade named

A contractor who frames houses and also hangs drywall has two rows in play, and the chart’s second step decides between them: “Then select the activity that best identifies the principal source of your sales or receipts”. Whichever trade brings in the larger part of the receipts is the one the rule points to. A person who runs two separate businesses is in a different position, because “If you owned more than one business, complete a separate Schedule C for each business.”

The chart has no row that names a general contractor. The closest wording is the building construction pair, “Residential building construction” and “Nonresidential building construction”, and the specialty rows above. Someone who hires out every trade and keeps none of the work in house still has to read those rows against what actually produces their receipts; the chart does not settle it for them.

Where the code goes next

Once you have a row, the code goes on line B next to the line A description on Schedule C (Form 1040). The money side of a construction business runs through the same schedule: gross receipts are covered on Schedule C line 1, work done by subcontractors on lines 10 and 11, and truck use on lines 8 and 9.

Edition and chart year

This page reads the 2025 Schedule C (Form 1040) and its 2025 instructions, the current files irs.gov served on 2026-10-23 (byte-identical to the archived copies). They are the files for the tax year 2025 return, filed in 2026. The schedule says “Attach to Form 1040, 1040-SR, 1040-SS, 1040-NR, or 1041”. Check the tax year printed on the schedule you are filling in and use the chart that comes with that year’s instructions, because a different year’s chart can list different codes or reword them.

Common mistakes

• Reading the chart as a list of job titles. The IRS says the codes “classify sole proprietorships by the type of activity they are engaged in”, so each row is an activity, and a title that is not on the chart is matched to the activity behind it.
• Stopping at the first trade row. The rule’s second step looks for “Then select the activity that best identifies the principal source of your sales or receipts”, which can be a different trade from the one you started with.
• Treating two trades under one name as a single Schedule C. The instructions say “If you owned more than one business, complete a separate Schedule C for each business.”

Related: Schedule C (Form 1040), Schedule C line 1, Schedule C lines 10 and 11, and Schedule C lines 8 and 9.

Sources

• Instructions for Schedule C (Form 1040), Profit or Loss From Business (2025): https://www.irs.gov/pub/irs-pdf/i1040sc.pdf
• Schedule C (Form 1040), Profit or Loss From Business (2025): https://www.irs.gov/pub/irs-pdf/f1040sc.pdf

Read from the IRS documents linked above on October 23, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.