42 — Cost of Goods Sold Calculated Updated for tax year 2025

What this line means

Line 40 minus line 41. This is the calculated cost of goods sold — the total cost of products you actually sold during the year. You carry this number to line 4 in Part I. The formula is: beginning inventory plus purchases, labor, materials, and other costs, minus ending inventory equals the cost of what you sold.

Does this apply to you?

• Every filer who completes Part III reaches this calculated line
• Tax software calculates this automatically from lines 40 and 41
• Paper filers subtract line 41 from line 40

Easy to overlook

This number flows to line 4 and must match The amount on line 42 should be entered on line 4 in Part I. If the two numbers do not match, the IRS will flag the discrepancy. Tax software handles this automatically, but paper filers must manually transfer the number and double-check it. ¹ [SOURCE: IRS Schedule C instructions — Part III, Line 42]

A negative result means something is wrong If line 41 (ending inventory) is larger than line 40 (total costs plus beginning inventory), the result is negative. This means you ended the year with more inventory value than you started with plus everything you added — which usually indicates an error in beginning inventory, purchases, or ending inventory valuation. ² [SOURCE: General filing pattern — COGS calculation errors]

Watch out for this

Entering a cost of goods sold amount on line 4 without completing Part III. If you claim any amount on line 4, the IRS expects a completed Part III showing how you arrived at that number. Entering a round estimate on line 4 without supporting detail in Part III invites scrutiny.

Related lines on your return

• Line 4 — Schedule C — Cost of goods sold in Part I; this number is carried there
• Line 40 — Schedule C — Total of lines 35-39; the starting point for this subtraction
• Line 41 — Schedule C — Ending inventory; subtracted to arrive at goods actually sold
• Line 5 — Schedule C — Gross profit; line 3 minus line 4