2023

For tax returns, the form year is the one for the first day of the year, not the last. Therefore, a June 30, 2023 return is filed on a 2022 form.

Calendar years begin on Jan 1, 2023, it goes on 2023 form.

Yours is a short-year 2023.

1040 or 1120?

With the possible exception of a NJ corp, the answer is the same.

A Schedule C filer has to do a short-year return?  The guy's not dead, he just closed the business.  

Dead or alive, it still goes on a 2023 return 

But if the 2023 forms are not yet available for an 1120 filer, you can use the 2022 form and cross out the year.  Usually these short-year questions involve what form to use.  As does this one.  

For a short year ended 12/15/23, I'd wait for the 2023 forms.

So would I, if the client is an 1120 filer.  That's why I asked.