Example, porch repair. I purchase materials like lumber, do the work, leave any unused materials in possession of my client, and bill my client for labor and materials.
The software isn't giving me an obviously correct way to include expenses like purchasing materials, so it's calculating my self employment tax based on my gross income, not my net income.
I don't think this stuff belongs in Schedule C Part III, because I'm not really "manufacturing good for sale", but i could be wrong?