I have a new client that asked me to amend last year's 1040 because they did not include business expenses when the previous person completed the return.  I assumed it was an LLC and Schedule C was needed. I am new to business returns with experience with just completing Schedule C.  

After further discussion the business has an S Corp election (started in 2020 but never had business activity until 2022). With an S Crop election can a Schedule C be completed or is 1120S the only option?

The client does not have a balance sheet just expenses and no income.  Can 1120S be completed without a balance sheet?