What Is MB Tax? Michigan Business Tax Rates, Filing, and Phaseout

The Michigan Business Tax is a legacy state tax that once applied broadly to businesses operating in Michigan but was replaced by the Corporate Income Tax for most filers starting January 1, 2012. It still exists today only for a narrow group of taxpayers that hold certificated credits — formal, state-issued tax credit agreements that predate the switch — and it is scheduled for full repeal for tax years beginning after December 31, 2031, or sooner if the last certificated credit is fully claimed.¹

If your business doesn’t hold one of those credits, you file under the Corporate Income Tax at a flat 6% rate and have no MBT obligation.² If you do hold one, the rest of this article is for you.

Who Still Files Under the Michigan Business Tax

Since 2012, only businesses holding an unused certificated credit may elect to file under the MBT instead of the CIT.³ The qualifying credits include:

MEGA employment tax credits, awarded by the Michigan Economic Growth Authority for job creation commitments
Brownfield redevelopment credits for environmental cleanup and redevelopment of contaminated properties
Historic preservation credits for rehabilitation of qualified historic structures
Film production and infrastructure credits
Anchor company credits for payroll and taxable value commitments by large employers
Farmland preservation credits
A handful of narrower credits: NASCAR speedway and safety, Michigan Early Stage Venture Investment vouchers, photovoltaic, federal contracts, polysilicon, battery pack, renaissance zone, and hybrid technology research and development credits

The Michigan Department of Treasury maintains the full list.⁴

How the Tax Is Calculated

The MBT has three parts, and all three need to be computed to see what you actually owe.

Business Income Tax at 4.95%

The first component applies a 4.95% rate to taxable income allocated or apportioned to Michigan.⁵ The starting point is federal taxable income, adjusted by additions and subtractions required under the MBT Act.

Modified Gross Receipts Tax at 0.8%

The second component is 0.8% on modified gross receipts apportioned to Michigan.⁶ Modified gross receipts are total receipts minus “purchases from other firms,” a defined category that covers inventory, depreciable assets, materials and supplies, staffing-company personnel costs, and construction subcontractor payments.⁷ Sales tax and other taxes collected from customers are excluded from gross receipts.

The 21.99% Surcharge

After computing the combined business income tax and modified gross receipts tax, you add a 21.99% surcharge on that combined liability (after allocation and apportionment, before credits).⁸ Insurance companies and financial institutions are exempt. For everyone else, this is a substantial addition: $100,000 in combined business income and modified gross receipts tax carries another $21,990 in surcharge before any credits apply.

The Election Is Binding

Choosing to file MBT instead of CIT is voluntary, but it locks you in. A business that files an MBT return and claims a certificated credit must keep filing under the MBT every subsequent year until the credit and any carryforward are fully exhausted.¹ The election cannot be revoked by amended return.³

That makes the math worth doing carefully. Compare the value of the remaining credits against what you would owe under the CIT’s flat 6%, remembering to include the surcharge in the MBT side of the calculation. If the credits comfortably offset the MBT bill, staying on it saves money. If the credits are nearly used up and the MBT liability is higher than the CIT alternative, letting the remaining credits go may be the cheaper outcome.

Taxpayers holding Brownfield redevelopment credits or MEGA credits can make the election in the year the credit first becomes available, rather than only in the first tax year after 2011. Once that specific credit is fully used, however, the taxpayer is no longer eligible to file MBT and cannot continue claiming other remaining certificated credits that were not the basis for the election.¹

Credit Recapture

If you claimed an MBT credit and later sell, dispose of, or move the qualifying asset out of Michigan, the state can require you to pay back some or all of the credit. The Schedule of Certificated Credits (Form 4947) calculates the recapture.⁹

Recapture applies to several credit types:

The MBT Investment Tax Credit, triggered when depreciable assets that qualified for the credit are sold or transferred outside Michigan, even to another member of the same unitary business group
The Brownfield Redevelopment Credit, if project conditions are not met
The MEGA Federal Contracts Credit, when contract-related conditions lapse
The Film Infrastructure Credit, Anchor Company Credits, and Start-Up Business Credit, each with their own triggers

Moving a credited asset across state lines is one of the most common triggers. Businesses operating in more than one state should track the location of credited property carefully.

Unitary Business Groups File One Return

When related businesses operate as a unitary business group (UBG), they file a single combined MBT return. A UBG exists when one member owns or controls more than 50% of the voting or comparable ownership interests of the others, and the businesses share a flow of value or are operationally integrated.

On the combined return, intercompany transactions are eliminated from the tax base, the apportionment formulas, and the calculation of exemptions and credits.¹⁰ If any single member of the group holds a certificated credit and elects MBT, the entire group files under the MBT and pays any resulting tax.¹

Deadlines, Estimated Payments, and Filing

The MBT annual return is due the last day of the fourth month after the tax year ends. For calendar-year filers, that’s April 30.¹¹ Fiscal-year filers apply the same four-month rule to their own year-end. A federal filing extension automatically extends the Michigan filing to the last day of the eighth month after the original due date, but the extension covers the filing only. Payment is still due by the original deadline.

Businesses expecting MBT liability over $800 for the year must make quarterly estimated payments. Calendar-year filers pay on April 15, July 15, October 15, and January 15.¹¹ Fiscal-year filers pay on the 15th day of the first month after each quarter ends. Underpayment carries its own penalty and interest, separate from the annual return.

The main filing document is the MBT Annual Return (Form 4567), used to calculate both taxes, apply the surcharge, and claim credits.¹² Businesses claiming certificated credits attach the Schedule of Certificated Credits (Form 4947) with documentation. Treasury encourages electronic filing through Michigan Treasury Online (MTO). New filers register through MTO with their FEIN.¹³ Paper returns can be mailed to the Department of Treasury in Lansing with all supporting schedules.

Penalties and Interest

Late filing or underpayment triggers a penalty starting at 5% of the unpaid tax for the first two months. Another 5% is added for each subsequent month or partial month the tax remains unpaid, capped at 25% total.¹⁴

Interest runs on top of the penalty. From January 1, 2026, through June 30, 2026, the annual interest rate on unpaid tax is 8.48%, one percentage point above the adjusted prime rate charged by commercial banks.¹⁵ Treasury resets the rate every six months. Interest compounds daily on the outstanding balance, and a filing extension does not pause it.

When the MBT Goes Away

The entire MBT Act is scheduled for repeal for tax years beginning after December 31, 2031.¹ It could end sooner. Under the enacting language of the 2011 reform, the Act is repealed on the date the Secretary of State receives written notice from the Department of Treasury that the last certificated credit (and any carryforward from it) has been fully claimed. Whenever that happens, every remaining business will file under the Corporate Income Tax, and the MBT will be fully retired.

1
Michigan Legislature. Michigan Code 208 – MCL Section 208.1500 – Taxpayer With Certificated Credit or Unused Carryforward
2
Michigan Legislature. Michigan Code 206 – MCL Section 206.623 – Corporate Income Tax
3
Michigan Department of Treasury. What Are the Filing Requirements for the Michigan Business Tax (MBT)?
4
Michigan Department of Treasury. CIT Credits
5
Michigan Legislature. Michigan Code 208 – MCL Section 208.1201 – Business Income Tax
6
Michigan Legislature. Michigan Code 208 – MCL Section 208.1203 – Modified Gross Receipts Tax
7
Michigan Legislature. Michigan Code 208 – MCL Section 208.1113 – Definitions G to O
8
Michigan Department of Treasury. Surcharge
9
Michigan Department of Treasury. 2024 Michigan Schedule of Certificated Credits Instructions
10
Michigan Legislature. Michigan Code 206 – MCL Section 206.691 – Unitary Business Group Combined Return
11
Michigan Department of Treasury. Filing Due Dates
12
Michigan Department of Treasury. 2025 Michigan Business Tax Annual Return Form 4567
13
Michigan Department of Treasury. MTO Registration
14
Michigan Department of Treasury. 2024 Michigan Business Tax Penalty and Interest Form 4582
15
Michigan Department of Treasury. Revenue Administrative Bulletin 2025-13 Interest Rate