City of Detroit Bulk Filing Transition

In November 2026, bulk filing for Detroit Employer Withholding Tax will move from Michigan Treasury Online (MTO) to the new Michigan Treasury eServices platform. Part of this change is to prepare for Treasury’s City of Flint income tax administration on January 1, 2027. After the transition, software providers will use the MiTreasury eServices-Business Portal to upload Detroit Employer Withholding Tax bulk files.

Other taxes currently bulk filed in MTO, including Michigan Sales, Use, and Withholding (SUW) Taxes, will remain in MTO. During the Detroit Employer Withholding Tax bulk file transition, bulk file in MTO for SUW taxes will only experience a brief outage.

• October 1 through October 15, 2026: Bulk file and pay September 2026 or third quarter 2026 Detroit Employer Withholding Tax timely in MTO Bulk E-File Guest Service or the web service by October 15.
• October 30, 2026:
  • Detroit Employer Withholding Tax bulk upload via MTO will end at 5 p.m., with acknowledgments made available by 6 p.m.
  • Detroit Employer Withholding Tax bulk upload via the Web Service will pause at 5 p.m.
  • SUW tax submissions via MTO bulk upload and the Web Service will pause at 5 p.m. and will resume at 11:59 p.m.
• October 30 through November 11, 2026: Bulk filing Detroit Employer Withholding Tax will not be available in any web platform or service. Late filing and payment may incur penalties and interest because Detroit Employer Withholding Tax returns and payments cannot be submitted by bulk and other electronic and paper submissions will be held for processing during this period.
• November 12, 2026: Bulk file for Detroit Employer Withholding Tax resumes in production at 7 a.m. It is important to note that the file format will remain the same despite the upload location changing:
  • Web Platform – Michigan Treasury eServices: www.michigan.gov/mitreasuryeservices 
  • Web Service (new): https://treasbulk.michigan.gov/michiganbulkfile

Michigan Treasury eServices uses MiLogin; MiTreasury eServices – Business Portal leverages the MiLogin for Business environment.

MiLogin is the State of Michigan’s identity management and authentication network for online platforms. MiLogin streamlines the public’s interactions by eliminating the need for different user profiles (username and password) for web applications across and within state departments. Your MiLogin profile is personal – regardless of the MiLogin environment the web application leverages for sign in services. It is essential to use MiLogin correctly; ensure your profile information is specific to you and up to date.

If you already have a username and password for any of the following web platforms, you can use the same credentials to log in to the MiTreasury eServices – Business Portal:

• Michigan Treasury Online (MTO),
• Business Tax eService,
• Collections eService (business services and account representative services portals), or
• any other State of Michigan online service within MiLogin for Business.

You can check whether your email address is associated with a MiLogin for Business user profile by looking up your MiLogin for Business user ID.

Beginning November 12, 2026, you will be to upload bulk files through Michigan Treasury eServices.

1. Go to michigan.gov/mitreasuryeservices.
2. Select the MiTreasury eServices – Business Portal.
3. Use the Sign in with MiLogin for Business button.
4. From the Summary page, in the Submit Forms section, use the "File a Tax Return" link.
5. On the File a Tax Return page, in the Bulk City Withholding section, use the “Submit Bulk City Withholding XML Upload” link.

Contact Treasury at MIFormsEfile@michigan.gov.