All domestic entities elected to be taxed as 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.