If I request an extension of time to file the 2020 Michigan Individual Income Tax Return, MI-1040, is my return now due on November 15, 2021 instead of October 15, 2021?

No. The extended MI-1040 due date remains October 15, 2021 for all taxpayers that receive an extension of time to file a 2020 tax return.  Taxpayers may file an application and pay any tax due with that extension request by May 17, 2021, the due date of the return remains October 15, 2021.