The following links provide information and technical guidance for Software Developers and Transmitters who are interested in developing software for the Modernized e-File Individual Tax Return Program. You will find XML Schemas, Business Rules, and other useful information and documents by tax year. Production and Acceptance Testing System (ATS) schema and business rules by tax year Tax year Form types 2024 1040, 1040-NR, 1040-SS (sp), 4868, 2350, 9465,56 2023 1040, 1040-NR, 1040-SS (sp), 4868, 2350, 9465, 56 2022 1040, 1040-NR, 1040-PR, 1040-SS, 4868, 2350, 9465, 56 2021 1040, 1040-NR, 1040-PR, 1040-SS, 4868, 2350, 9465, 56 Software testing Tax Year test scenarios can be found on the Modernized e-File (MeF) Assurance Testing System (ATS) page. Stylesheets Individual Tax Return and Extensions stylesheets can be downloaded for use in displaying XML tax return data and are located on the MeF stylesheets page. Instance document A Send Submissions sample can be found in Section 4.3.1 of the MeF State and Trading Partners ICD, which is located on the MeF user guides and publications page. IRS e-signature option for taxpayers currently using Forms 8878 or 8879 Frequently asked questions for IRS e-file signature authorization MeF schemas and business rules MeF program information