This depends on what type of entity your small business is:
Sch C or Sch F....depends on your other income and follows the filing requirements of 1040...but, if net income from the business is over $400, filing is required for SE tax, regardless of other income and filing requirement
Corporation...must be filed
https://www.irs.gov/pub/irs-pdf/i1120.pdf
Elected 1120S status
https://www.irs.gov/pub/irs-pdf/i1120s.pdf
If a partnership
https://www.irs.gov/pub/irs-pdf/i1065.pdf
**Disclaimer: Effort has been made to offer correct information; but due to the discussion forum limitations, the poster disclaims any legal responsibility for the accuracy of the poster's response**
