The only module the Lacerte software is capable of e-filing multiple year returns in one year's program for a short period 2023 is the "Exempt Org. Tax" module. I know this because I have actually already utilized it this year. Yes, I had to call Lacerte to have a person "update the processing" on their end, but once they did, I could see it was successfully submitted to the IRS the same day as submission - I speaking of the short-period 2023.

And yes, the girl gave me the same spiel about how the IRS cannot accept multiple year submissions within one year prior to her seeing it with her own eyes that both were submitted and accepted successfully.

Now, does this mean that the IRS is only setup for  "Exempt Organization" multi-year filing, in one filing period, or does it mean Lacerte's software has only been updated that far? I do not know.

But I am still waiting on the tech people to fix the Illinois/New York State algorithm that incorrectly apportions income since 2017. So I'm not really holding my breath here on the former being true.