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) 2020. Developers and other Authorized IRS e-file Providers can find information on e-filing returns through MeF in the Publication 4163PDF and Publication 4164PDF. 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 Memos - 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 2020 Documents Tax Year 2020 1065 MeF Accepted Forms and Schedules PDF Tax Year 2020 1065 MeF Forms Attachment ListingXLSX Tax Year 2020 1065 MeF Return Due DatesPDF Tax Year 2020 Stylesheets: MeF Stylesheets Tax Year 2020 Known Issues and Solutions XLSX– Revised 02/23/2023 Form 1065 links to TY2020 Release Memos Version Available Date ATS Date Production Date Comments 2020v5.2 10/14/2021 Start: 11/21/2021 End: TBD Start: 01/07/2022 End: TBD 03/31/2022 Business Rules updates provided Complete package available including Business Rules 2020v5.1 02/09/2021 Start: 03/07/2021 End: TBD Start: 03/21/2021 End: TBD 08/19/2021 Business Rules updates provided 04/22/2021 Business Rule updates provided 2020v5.0 11/16/2020 Start: 12/13/2020 End: TBD Start: 01/08/2021 End: TBD Current Valid XML Schemas and Business Rules for 1065 Modernized e-File (MeF) Modernized e-File (MeF) Schemas and Business Rules