Sept 15 : Form 1120S for calendar year S Corporations that timely filed extensions due to the IRS. Form 1065 for calendar year partnerships that timely filed extensions due to the IRS. No more extensions.
Oct 15 : Form 1040 for taxpayers who timely filed extensions due to IRS. Form 1120 for taxpayers that timely filed extension due to the IRS. No more extensions.
Oct 31 : 2023 Q2 Form 941 due to the IRS. 2023 Q2 wage reporting due to state employment agencies.