If you are the sole owner of a business or operate as an independent contractor, you will need to file a Schedule C to report income or loss from your business activities.
If you have $400 or more of business income over and above your expenses, you need to file a Schedule C or C-EZ, and a Schedule SE to pay self-employment tax, even if you would not otherwise have enough income to be required to file a tax return.
The files are in Adobe Portable Document Format (.pdf), and you will need the free Acrobat Reader to view and print the files.