Some benefits of filing through Modernized e-File (MeF) are: Year Round Filing – Returns filed through MeF can be submitted year round. Prior Year Returns – MeF allows filing of prior year 1040 returns. As a new tax form type is added to the MeF platform, tax returns will be accepted for the current tax year only. As subsequent tax years are added to the system, MeF will accept the current tax year and two prior tax years. For example: In January 2015, 1040 MeF accepted Tax Years 2014, 2013, and 2012. In January 2016, 1040 MeF accepted Tax Years 2015, 2014, and 2013. Note: MeF does not accept prior year extensions (Forms 2350 and 4868) Binary Attachments – The MeF program allows forms not already developed in XML to be attached to the electronic submission to accommodate late legislation and other unscheduled form changes. Note: MeF currently only supports PDF format. Download the most recent version of Adobe Acrobat Reader. More Explicit Error Conditions - Error explanations (Business Rules) pinpoint the location of the error in the return and provide complete information in the acknowledgement file that is passed back to the transmitter. Under the previous 1040 e-file program, one error code may have applied to multiple types of e-file error conditions. MeF error codes use simple wording to clarify each error that triggers a rejection. You can find additional information on Modernized e-File on the MeF Overview Page, which includes information and links on: Design history. Processing of returns. Communication between IRS and transmitters during the e-file process. Approval of tax preparation software. Security during transmission. 1040 MeF Program Page MeF Program Information Page