If you are the sole owner of a business (operating as a sole proprietorship or a single member LLC disregarded as an entity for tax purposes) or operate as an independent contractor, you will need to file a Schedule C to report income or loss from your business activities. The Schedule C is attached to your Form 1040.
If your business has $400 or more of business income over and above 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 latest version of the Schedule C form and instructions can be found on the IRS’ website.
The files are in Adobe Portable Document Format (.pdf), and you will need Acrobat Reader to view and print the files.