You can't change a return from an S-Corp to a C-Corp. You will have to start a new return. When you start the return, be sure to indicate that you did NOT use QuickBooks. You will then be prompted to select what type of return you want to create. You will select C Corporation (Form 1120). See screenshot below. You can use the new return to file your extension, and then continue using the old S-Corp (1120-S) to prepare the company's tax returns.

**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"