Michigan Is Moving Tax Services. Here's What Businesses Could Lose Access to Before November 12.

Michigan is moving several tax services onto an expanded online platform on November 12. For businesses and tax preparers, the immediate question is what happens before that date: some online functions are temporarily unavailable, others have been retired, and many familiar tax services are not moving permanently at all.

The distinction matters for businesses trying to register, file or pay taxes this week. The Michigan Department of Treasury has published different interruption periods depending on the tax and online system. A business that assumes every filing function will remain down until November 12 could be wrong. So could a taxpayer expecting an old city-tax or motor-fuel portal to return after maintenance.

Treasury says the expanded Michigan Treasury eServices platform is scheduled to offer additional functions starting at 7 a.m. on November 12, 2026. Affected programs include Detroit city income taxes, motor-fuel and tobacco taxes, certain marijuana-related taxes, Detroit employer-withholding bulk filing, and the state's 9-1-1 program.

Ordinary sales, use and withholding tax filings are generally staying in Michigan Treasury Online, or MTO.

Which Michigan tax services are unavailable, and when?

Treasury's announced windows are not identical. The following reflects its published transition schedule as of November 5, 2026.

November 4–5: Temporary business-tax interruptions

The Business Taxes eService and MTO's regular business-tax functions, including sales, use and withholding, are scheduled to be unavailable from November 4 at 12:01 a.m. through November 5 at 11:59 p.m.

Most of those functions are expected to return to their existing platforms after maintenance. They are not all moving permanently to the expanded system.

October 30–November 12: Retired systems and migrating functions

Several older services were scheduled to shut down October 30 at 5 p.m.

These include the former Detroit city-tax eService and ePayments sites, along with the Michigan Motor Fuel and Tobacco Tax System, commonly called MiMATS.

The affected functions are scheduled to become available through Michigan Treasury eServices on November 12 at 7 a.m.

Certain functions previously available in MTO, including Marijuana Retailers Excise Tax and Detroit employer-withholding bulk filing, are also transitioning to the expanded platform.

November 4–12: Existing eServices portal interruption

Treasury separately announced that specified existing eServices citizen and business portal functions would be unavailable beginning November 4 at 11 p.m., with expanded service scheduled to resume November 12 at 7 a.m.

These different timelines explain why a blanket announcement that Michigan's tax websites are closed until November 12 can be misleading. Businesses need to identify the particular tax service they use.

What is moving to Michigan Treasury eServices?

Detroit city income taxes

Michigan is migrating Detroit's individual and business income-tax administration to its modernized tax system.

Affected taxpayers will have expanded online options to file returns, make payments and manage accounts. Treasury has also announced revised forms and procedures, including changes affecting amended Detroit business returns.

Businesses with Detroit tax obligations should check the requirements for their particular return rather than assume that every city-tax filing follows the same process.

Motor-fuel and tobacco taxes

MiMATS was scheduled to close October 30 at 5 p.m. Its functions are moving into the eServices business portal on November 12.

Fuel distributors, tobacco businesses and other affected filers should review Treasury's transition guidance, particularly where required filings or payments fall near the interruption period.

A temporary portal closure should not be assumed to extend an existing tax deadline.

Marijuana taxes and employer withholding

Marijuana Retailers Excise Tax and Detroit employer-withholding bulk filing are moving from MTO to the expanded platform.

The Wholesale Marijuana Tax program will also gain additional online filing and account-management functions.

For Detroit employers using bulk filing, the distinction is especially important. Detroit employer-withholding bulk submissions are affected by the transition, but ordinary state sales, use and withholding bulk filing remains in MTO.

Treasury indicates that the Detroit bulk-submission file format will remain the same even though the upload destination changes.

Michigan's 9-1-1 program

The state is adding online filing and payment functionality for its 9-1-1 program.

Affected retailers and service suppliers should consult the program-specific modernization instructions to determine when the new functions become available.

What's staying in Michigan Treasury Online?

Many Michigan businesses will continue using familiar tax services after the transition.

Regular sales, use and withholding tax filing remains in MTO. Treasury also lists other business-tax registration, payment and account functions that are scheduled to resume through existing systems after the shorter maintenance interruption.

That creates an important distinction: a company may need the expanded eServices platform for one tax program while continuing to use MTO for another.

The safest approach is to identify the specific tax account first and then follow Treasury's instructions for that account.

Phone support is affected, too

Treasury has also announced temporary interruptions to several tax-related call centers.

Business-tax phone lines are scheduled to close November 4–5.

City income-tax, motor-fuel, tobacco, marijuana and miscellaneous-tax phone support is scheduled to close November 4–6.

Individual income-tax phone lines are scheduled to close November 5–6, while collections services will operate with limited availability from November 4–6.

These interruptions do not necessarily change underlying filing or payment deadlines.

Five things Michigan businesses should check before November 12

1. Identify the tax program involved. State sales taxes, Detroit income taxes, motor-fuel taxes and marijuana-related taxes do not all follow the same transition schedule.

1. Determine whether the existing system is returning. Many MTO services are scheduled to resume after the shorter November 4–5 interruption, while MiMATS and former Detroit city-tax services are being replaced.

1. Review outstanding returns and payments. Do not assume that an online service interruption automatically extends a statutory deadline.

1. Confirm account-access requirements. Treasury provides program-specific instructions, and some existing MiLogin profiles may remain usable.

1. Recheck the department's instructions on or after November 12. The announced 7 a.m. launch is a scheduled time, not a guarantee that every function will immediately be available.

One modernization, several different filing paths

Treasury describes the expansion as an effort to simplify online tax administration.

But the implementation schedule shows that moving a tax program, retiring an older portal and temporarily closing a website for maintenance are three different things.

A retailer filing ordinary Michigan sales taxes, a Detroit business reporting city income taxes and a fuel distributor that previously used MiMATS face different changes.

Businesses trying to avoid delays should match each obligation to its correct system rather than rely on a general announcement about the transition.

For the latest information, consult the Michigan Department of Treasury's official eServices guidance and service-by-service interruption schedule:

https://www.michigan.gov/taxes/mitreasuryeservices

https://www.michigan.gov/taxes/mitreasuryeservices/enews/impacts/web-platform-impacts

Read the supporting source.

Spot an error? Email [email protected]. We fix mistakes and note the change. See our corrections policy.