Schedule C is the tax form used by sole proprietors and single-member LLCs to report business income and expenses. Your net profit (income minus expenses) flows to your Form 1040 and is subject to both income tax and self-employment tax. You deduct things like advertising, supplies, home office, and vehicle expenses here. If you have multiple businesses, you file a separate Schedule C for each. Keeping organized records all year makes completing Schedule C much easier.