If you're a sole proprietor, your entire tax life lives on one form: Schedule C. In this episode, Lauren walks through how Schedule C actually works — income reporting, cost of goods sold, deductible expenses, and the specific areas where IRS examiners find problems. She also covers the number that surprises almost every new business owner: self-employment tax. What it is, how it's calculated, and why not planning for it is the most common reason sole proprietors end up with a tax bill they didn't see coming.