All domestic entities elected to be taxed as a corporation must file form 1120 for every tax year regardless of their taxable income. The due date to file this form is July 15. If a business is not able to file their return on time, an extension of time up to three months can be sought by filing Form 7004.
When you file a tax extension for C Corp with ExpressExtension, choose the Business Entity Type as 'Corporation' and the Form Type as 'Form 1120- US Corporate Income Tax Return'.
For step-by-step instructions on e-filing Form 7004, click here.