The links below provide information and technical guidance for Software Developers and Transmitters who are interested in developing software for the Modernized e-File (MeF) Forms 1120, 1120-F, and 1120-S for Tax Year 2021. Developers and other Authorized IRS e-file Providers can find information on e-filing returns through MeF in Publication 4163 PDF and Publication 4164 PDF. Directions for Corporations required to e-file can be found through the e-file for Large and Mid-Size Corporations website. Test Scenarios for the 1120 Form Family can be found on the Modernized e-File (MeF) Assurance Testing System (ATS) page. Extensible Markup Language (XML) Schemas, Business Rules, and Release Memorandum - Throughout the year, multiple versions of these documents may be in use at the same time. Special attention should be paid to the Release Memo issue date and the projected start and end dates for Assurance Testing System and Production. Form 1120 Schemas and Business Rules are now distributed through the Registered User Portal and your e-services mailbox. This mailbox is part of the Secure Object Repository (SOR). Users will access their mailbox in their existing e-services account to pick up the Schemas and Business Rules packages. Instructions for accessing the SOR mailbox Tax year 2021 documents Tax Year 2021 1120 MeF Accepted Forms and Schedules PDF Tax Year 2021 1120 MeF Forms Attachment Listing XLSX Tax Year 2021 1120 MeF Return Due Dates PDF Tax Year 2021 Stylesheets: MeF Stylesheets Tax Year 2021 Known Issues and Solutions XLSX – Revised 03/26/2024 Form 1120, 1120-F, 1120-S links to TY2021 release memos Version Available Dates ATS Dates Production Dates Comments 2021v4.4 02/09/2023 Start: 03/05/2023 End: TBD Start: 03/19/2023 End: TBD 12/28/2023 Business rule updates provided ATS and production dates TBD for processing year 2024 11/13/2023 Business rule updates provided Valid for ATS and Production 2021v4.3 04/21/2022 Start: 06/05/2022 End: TBD Start: 07/24/2022 End: TBD 07/20/2023 Business rule updates provided 11/29/2022 Business rule updates provided 11/14/2022 Business rules updates provided 09/01/2022 Business rules updates provided. 07/21/2022 Business rules updates provided ATS and production dates TBD for processing year 2023 07/20/2022 Version 2021v4.3 not available in ATS between 07/17/2022 through 07/24/2022 06/09/2022 Business rules updates provided 05/03/2022 The entire package will be available for production 07/24/2022. 04/21/2022 The Form 1120-S Schedules K-2 and K-3 will be available in production 07/24/2022. 03/17/2022 An early look of Tax Year 2021/ Processing Year 2022 Form 1120-S Schedules K-2 and K-3 schema only. Related business rules will be made available later. 2021v4.2 02/10/2022 Start: 03/06/2022 End: TBD Start: 03/20/2022 End: TBD 2021v4.1 11/12/2021 Start: 12/12/2021 End: TBD Start: 01/07/2022 End: TBD 2021v4.0 10/14/2021 Start: 11/21/2021 End: TBD Start: 01/07/2022 End: TBD Current valid XML schemas and business rules for 1120/1120-F/1120-S Modernized e-File (MeF) schemas and business rules
