The IRS's Modernized e-File System will shut down from 10 p.m. Eastern on Saturday, August 31, until noon Eastern Standard Time on Tuesday, September 3.
The service is completing a multi-year upgrade to the online portal infrastructure and the MeF app version, and current supported schemas won't change as part of this migration, according to the IRS.
The first phase of the upgrade involved the transition to a new IRS.gov in August of last year. The second phase supports all registered user applications and occurs over Labor Day weekend. Full operation resumes September 3.
The MeF Production and Assurance Testing System will be migrated to the new portal and fully operational to all software developers, transmitters and states on September 3 at noon EST.
More information is available from the IRS here.
Routine system maintenance will occur every Sunday from 1:00 a.m. to 7:00 a.m. EST.