What is Schedule C?

Schedule C is the IRS form used by sole proprietors to report business income and expenses, attached to the personal Form 1040 to calculate net profit or loss from self-employment. For professional service firm owners operating as sole proprietors, Schedule C is the primary business tax form determining taxable income and self-employment tax.

Key characteristics

• Reports sole proprietor income

• Attached to Form 1040

• Calculates net profit or loss

• Determines self-employment tax

• List income and expenses

• Required for sole proprietors

Why it matters for professional service firms

Schedule C determines how much of your business income is taxable and subject to self-employment tax. Accurate completion ensures proper deductions are claimed. Professional service firm owners filing Schedule C should understand expense categories and documentation requirements.

Real-world example

Marcus operated his consulting practice as a sole proprietor. Schedule C reported: gross receipts $285,000, expenses $78,000 (including home office $8,400, travel $12,000, supplies $4,200), net profit $207,000. Net profit flowed to Form 1040 line 8 and Schedule SE for self-employment tax calculation. Understanding Schedule C categories maximizes legitimate deductions.