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) Form 1065 for Tax Year (TY) 2021. Developers and other Authorized IRS e-file Providers can find information on e-filing returns through MeF in the Publication 4163 PDF and Publication 4164 PDF. Test Scenarios for Form 1065 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 (ATS) and Production. Form 1065 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 Schema and Business Rules packages. Instructions for accessing the SOR mailbox Tax year 2021 documents Tax Year 2021 1065 MeF Accepted Forms and Schedules PDF Tax Year 2021 1065 MeF Forms Attachment Listing XLSX Tax Year 2021 1065 MeF Return Due Dates PDF Tax Year 2021 Stylesheets: MeF Stylesheets Tax Year 2021 Known Issues and Solutions XLSX– Revised 03/26/2024 Form 1065 links to TY2021 release memos Version Available Date ATS Date Production Date Comments 2021v4.4 02/09/2023 Start: 03/05/2023 End: TBD Start: 03/19/2023 End: TBD 07/20/2023 Business Rules updates provided 11/13/2023 Business Rules updates provided 12/27/2023 Business Rules updates provided 2021v4.3 4/21/2022 Start: 06/05/2022 End: TBD Start: 06/19/2022 End: TBD 07/11/2022 Business Rules updates provided 2021v4.2 2/10/2022 Start: 03/06/2022 End: TBD Start: 03/20/2022 End: TBD 2/10/22: Tax Year 2021/ Processing Year 2022, Final Version 4.2 1065 Series Schema and Business Rules 12/22/21: An early look of Tax Year 2021/ Processing Year 2022 Form 1065 Schedules K-2 and K-3 schema only. Related business rules will be made available later 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 1065 Modernized e-File (MeF) Modernized e-File (MeF) schemas and business rules
