How to File a Schedule C the Right Way

File Schedule C correctly by organizing business income, maximizing deductions, and avoiding IRS red flags that trigger audits.

1. Calculate gross receipts and business income. Report all 1099s and cash payments on Line 1. Include credit card processing, checks, and digital payments. Subtract returns and allowances on Line 2. Your net business income goes to Line 3 and flows to your Form 1040.
2. Organize deductible business expenses by category. Use Part II to claim advertising, vehicle expenses, office supplies, professional services, and other ordinary business costs. Keep receipts for everything over $75. Vehicle expenses use either actual costs or standard mileage rate of $0.67 per business mile in 2026.
3. Handle home office deduction carefully. Claim home office only if you use the space exclusively for business. Simplified method allows $5 per square foot up to 300 square feet ($1,500 max). Actual expense method requires detailed utility and maintenance cost allocation. Both methods reduce your home sale exclusion.
4. Calculate and report cost of goods sold. Use Part III if you manufacture products or hold inventory. Add beginning inventory, purchases, and direct labor costs, then subtract ending inventory. Service businesses typically skip this section unless they resell products.
5. Review ratios that trigger audit flags. IRS computers flag Schedule C returns with expense ratios over 52% of gross income or large home office deductions. Business meals over 50% of travel expenses draw attention. Document everything and ensure expenses pass the ordinary-and-necessary test.
6. Complete self-employment tax calculation. Net profit from Line 31 flows to Schedule SE for self-employment tax calculation. You'll owe 15.3% on profits up to $168,600 (2026 wage base) plus 2.9% Medicare tax on all profits. Quarterly estimated payments reduce year-end tax bills.