Although the IRS now allows year-round electronic filing with the new MeF system, the IRS must shut down for a period of time for maintenance.
Per the IRS Modernized eFile (MeF) Operational Status webpage:
Shutdown begins on Saturday, November 18, 2023, at 11:59 p.m. Eastern time, in order to prepare the system for the upcoming Tax Year 2023 Filing Season.
Only "Send Submissions" for 1040 (both State and Federal) will be affected by this shutdown, all other services such as "Get Acks" and all state services will be available after the shutdown.
Shutdown for "Send Submissions" only is scheduled to begin at 11:59 a.m. (noon) Eastern time, Tuesday, December 26, 2023.
Transmitters can continue to use the other service requests except "Send Submissions" until 11:59 p.m. (midnight) Eastern time, Tuesday, December 26, 2023.
TaxAct will not allow 1040 e-filing as of this date to allow ample time for submitting of returns to the IRS by their shutdown date. Once the IRS e-filing shutdown period begins, taxpayers will need to paper file their tax return. Only preparers have the ability to submit prior year individual (1040) returns, and preparers and consumers who are filing business returns have the ability to submit prior year returns. Returns can be submitted as soon as the Final version of the TaxAct software is released in January, but the returns will not actually be submitted to the IRS until they are ready to start processing them. Once the IRS starts processing returns for the current year, a preparer can submit prior year returns.
Per the IRS Modernized e-File (MeF) Status webpage:
Business tax returns: January 18, 2024
Individual tax returns: January 18, 2024
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.