Michigan Form MI-1120, now officially issued as Form 4891, the CIT Annual Return, is the Corporate Income Tax return that every standard C corporation with nexus to Michigan and apportioned gross receipts of at least $350,000 must file with the Michigan Department of Treasury. The form reports the 6% Corporate Income Tax under Michigan Compiled Laws Chapter 206, Part 2, which replaced the old Michigan Business Tax in 2012.
A late or wrong MI-1120 sets off the Treasury’s automated matching system, which compares your federal Form 1120 to your Michigan return. According to the Treasury’s 2024 Annual Report, Michigan processed more than 95,000 CIT returns last year, and roughly 11% triggered an automated correction notice for math errors, missing schedules, or apportionment problems.
Here is what you will learn in this guide:
- 📋 How every line of Form 4891 (MI-1120) connects to your federal Form 1120 and what to write in each box
- 🧮 How to calculate the Michigan sales-only apportionment factor without overstating or understating your tax
- 💰 How to claim the Small Business Alternative Credit and the income, compensation, and shareholder tests that disqualify many filers
- 📅 The exact due dates, extension rules, and penalty math for late filing or late payment
- 📨 How to file by mail, through approved e-file software, or through Michigan Treasury Online (MTO)
What Form MI-1120 Is and Who Must File It
Form MI-1120, branded today as Form 4891 Corporate Income Tax Annual Return, is Michigan’s primary corporate tax return. It reports a flat 6% tax on apportioned and allocated business income for C corporations and entities taxed as C corporations under the Internal Revenue Code. The return is anchored to your federal taxable income, so the starting point on the Michigan form is the same number reported on federal Form 1120, Line 28.
Every C corporation with nexus to Michigan and apportioned or allocated gross receipts of at least $350,000 must file. Nexus is triggered by physical presence in Michigan or by $350,000 or more in Michigan-sourced sales under the economic nexus rule in MCL 206.621. Insurance companies file Form 4905 instead, and financial institutions file Form 4908 under the franchise tax rules.
S corporations, partnerships, sole proprietors, and single-member LLCs do not file MI-1120. S corporations flow through to the owners’ Michigan Individual Income Tax Return (Form MI-1040). Unitary Business Groups (UBGs) — two or more corporations with more than 50% common ownership and a flow of value — file the combined Form 4567 CIT Annual Return for Standard Taxpayers instead of a stand-alone MI-1120.
The agency that receives the form is the Michigan Department of Treasury, Corporate Income Tax Division. The statute that governs the tax is the Michigan Income Tax Act of 1967, as amended in 2011 to create the CIT. Late or missing returns trigger penalties under MCL 205.24, which we detail in the deadlines section.
Before You Start: Documents and Information You Need
Filing MI-1120 without your supporting documents is the fastest way to make a mistake. The form pulls numbers from your federal return, your sales records, your shareholder records, and your prior-year Michigan return. Gather these before opening the form so you do not have to stop and search mid-entry.
- Federal Form 1120 (complete copy, all pages and schedules): The Michigan return starts at federal taxable income on Line 28. Without the federal return, every downstream line is wrong.
- Your nine-digit Federal Employer Identification Number (FEIN): Treasury matches this number against IRS records, and a typo will reject the return.
- Your Michigan Treasury account number (if assigned): This appears on prior notices from Treasury. New filers leave this blank and Treasury assigns one.
- Sales records broken down by destination state: You need total everywhere sales and Michigan-destination sales to compute the apportionment percentage.
- Officer compensation records: Each officer’s W-2 wages are needed to test eligibility for the Small Business Alternative Credit under MCL 206.671.
- Shareholder ownership percentages: The Small Business Alternative Credit disqualifies any corporation with a shareholder owning more than 90% who also has allocated income above the cap.
- Prior-year MI-1120 or Form 4891: Needed for NOL carryforward amounts and to verify the prior-year tax liability for safe-harbor estimated payments.
- Estimated payment records (Form 4913 vouchers or MTO payment confirmations): You need the total of all four quarterly payments to fill in Line 38.
- Schedule of additions and subtractions: Items like state and local income taxes deducted federally must be added back, and interest from U.S. obligations must be subtracted.
- Apportionment workpapers: Throwback rules, dock sales, and sales to the U.S. government complicate the sales factor and need supporting math.
Where to Get the Form and How to Access It
Form MI-1120 (Form 4891) is published only by the Michigan Department of Treasury. Downloading from a third-party site risks getting a prior-year version, which Treasury will reject. The official PDF lives on the Michigan Treasury CIT Forms page, and the form is updated each December for the next filing season.
The 2025 tax-year form carries a revision date of 12-2025 in the bottom-left corner. Confirm this date matches the year you are filing for before you write a single number. Using the wrong year is the single most common rejection reason, because line numbers and credit thresholds change.
You can access the form three ways. The PDF download is fine for paper filers and for accountants who scan and store the completed return. Approved e-file software loads the current form automatically and pushes the return to Treasury through the Modernized e-File (MeF) system, the same backbone the IRS uses. The third path is Michigan Treasury Online (MTO), where you can file, pay, and track the return inside one portal.
If you need help in person, the Treasury’s Lansing office on Austin Building, 430 W Allegan Street, accepts walk-in questions during business hours. For mailed forms, the official version is the only one with the proper barcode that Treasury’s scanners read, so always download fresh rather than reusing last year’s saved file.
Step-by-Step: How to Fill Out MI-1120 (Form 4891) Line by Line
The 2025 Form 4891 is two pages long with 47 numbered lines. Work from top to bottom and do not skip ahead, because later lines depend on numbers you compute earlier. Every entry uses whole dollars, rounded — no cents, no commas, no dollar signs.
Tax Year Beginning and Ending Dates
This top field asks for the first and last day of your tax year. Calendar-year filers write 01-01-2025 and 12-31-2025. Fiscal-year filers write the actual start and end of their fiscal year, formatted MM-DD-YYYY with dashes. A corporation with a June 30 year-end writes 07-01-2024 through 06-30-2025.
For a short period — first year of operations, final return, or a year of change — the dates show only the months the corporation actually existed or operated. Lakeside Bottling Corp, formed on March 15, 2025, writes 03-15-2025 to 12-31-2025.
The most common mistake is leaving these dates blank or writing only the year. Treasury’s system will assume calendar year and may reject mismatched federal returns. People often think dates are optional for calendar filers, but they are required on every return.
Federal Employer Identification Number (FEIN)
This box asks for the nine-digit FEIN the IRS assigned to your corporation. Write it in the format XX-XXXXXXX with the dash. Treasury runs this number through an IRS match, and a single transposed digit will hold the return.
If your corporation went through a merger and now uses a new FEIN, file the final return under the old FEIN and the first return under the new one. Do not mix them on one form. The most common mistake is using the owner’s Social Security number instead of the FEIN, which causes Treasury to route the return to the wrong division.
A common misconception is that the FEIN can be left off if the return is filed with a Treasury account number. Both are required, and missing the FEIN is grounds for an automatic notice within 30 days.
Corporation Name and Mailing Address
Write the legal name of the corporation exactly as it appears on the IRS CP 575 notice that issued the FEIN. Lakeside Bottling Corporation is correct; Lakeside Bottling Corp. is not, unless the IRS issued the FEIN with that abbreviation. The mailing address goes on the lines below the name and uses standard USPS formatting.
If the corporation uses a P.O. Box for mail and a street address for legal service, put the P.O. Box on the address line. Treasury sends notices to whatever address sits on the return. A street address may also be required if the corporation has a foreign address; see the form instructions for the country code box.
The most common mistake is using a doing-business-as (DBA) name instead of the legal name. Treasury cannot match a DBA to the FEIN and will issue a name-mismatch notice. People often think the legal name and the trade name are interchangeable, but only the IRS-registered name is correct here.
Line 1: Apportioned and Allocated Federal Taxable Income
Line 1 asks for the federal taxable income from federal Form 1120, Line 28, before the net operating loss deduction and special deductions. Copy this number directly from your federal return. If federal taxable income is negative, write the amount with a minus sign — for example, -45,000.
Edge case: corporations that file a federal consolidated return must use the proforma 1120 for the Michigan filer only, not the consolidated number. Michigan does not allow federal consolidated filing.
The most common mistake is using Line 30 (federal taxable income after NOL) instead of Line 28. This understates Michigan tax because Michigan computes its own NOL. The misconception is that the federal NOL deduction carries through to Michigan automatically; it does not.
Line 2: Domestic Production Activities Deduction Add-back
Line 2 adds back any Domestic Production Activities Deduction (DPAD) the corporation claimed federally. Michigan does not allow this deduction. Write the deduction amount as a positive number; if you did not claim DPAD, write 0.
Edge case: for tax years 2018 and later, DPAD is repealed federally, so most filers enter 0. Older NOL carrybacks may still trigger an add-back.
A mistake here is leaving the line blank rather than writing 0. Blank lines flag the return as incomplete. The misconception is that Michigan automatically conforms to all federal deductions; it does not, and DPAD is one of the legacy disconformities.
Line 3: Interest Income from U.S. Obligations
Line 3 subtracts interest income from U.S. government obligations like Treasury bills and bonds. Michigan cannot tax this income under 4 U.S.C. § 113. Write the amount as a positive number; the form math subtracts it.
Edge case: interest from federal agencies like Fannie Mae or Freddie Mac does not qualify and stays in income. Only direct U.S. obligations get the subtraction.
The most common mistake is including municipal bond interest here, which is already excluded federally. The misconception is that all government interest is exempt; only direct U.S. Treasury and certain federal direct obligations qualify.
Line 4: Taxes Measured by Net Income
Line 4 adds back state and local taxes deducted on the federal return that are measured by net income. This includes the Michigan CIT itself, other states’ income taxes, and city income taxes like Detroit’s corporate tax. Write the total as a positive number.
Edge case: franchise taxes that are not measured by net income — like Texas margin tax or Delaware franchise tax — are not added back here. Only true income taxes count.
The most common mistake is including federal income tax in this add-back. Federal income tax is not deducted on federal Form 1120, so there is nothing to add back. The misconception is that all taxes deducted federally must be added back; only income-based taxes are.
Line 5: Other Additions
Line 5 captures other additions required by Michigan law, including bonus depreciation differences for certain pre-2008 assets and oil and gas income subject to severance tax. Attach Schedule of Additions (Form 4891 Worksheet) showing the breakdown.
Edge case: a corporation with no additions writes 0. Failure to attach the worksheet for a non-zero figure triggers a request-for-information letter.
The most common mistake is using Line 5 as a catch-all for items that belong elsewhere on the form. The misconception is that this line is optional; it is mandatory when any item applies, and Treasury cross-checks against federal Form 1120 Schedule M-1.
Line 6: Other Subtractions
Line 6 captures Michigan-specific subtractions, including dividends received from foreign operating entities and certain miscellaneous items listed in the instructions. Write the amount as a positive number.
Edge case: subtractions for income from Renaissance Zones go on a separate line, not here. Renaissance Zone income is reported on the Schedule of Renaissance Zone Credit (Form 4595).
The most common mistake is double-claiming a subtraction that was already removed at the federal level. The misconception is that any item that reduces income belongs here; only items expressly authorized by MCL 206.623 qualify.
Line 7: Business Income
Line 7 is the math result of Line 1 plus Lines 2, 4, 5, minus Lines 3 and 6. This is your business income before apportionment. Treasury’s e-file software calculates this automatically; paper filers must compute by hand.
Edge case: if the result is negative, this becomes your starting NOL for Michigan purposes. Write the negative number with a minus sign.
The most common mistake is a math error from miskeying one of the inputs. The misconception is that the federal NOL deduction reduces business income at this stage; it does not — Michigan NOLs are applied later on Line 23.
Line 8: Apportionment Percentage
Line 8 is the Michigan sales factor, calculated as Michigan sales divided by everywhere sales, expressed as a percentage rounded to six decimal places. A corporation with $2,000,000 in Michigan sales and $10,000,000 in everywhere sales writes 20.000000%.
Edge case: a corporation with sales only in Michigan writes 100.000000%. A corporation with no Michigan sales but physical nexus still writes the actual percentage, even if it is 0.000000% — they may still owe tax on allocated income.
The most common mistake is using a three-factor formula like the old MBT. The CIT uses a single sales factor only under MCL 206.661. The misconception is that property and payroll still matter for apportionment; they do not for the CIT.
Line 9: Apportioned Business Income
Line 9 multiplies Line 7 by the percentage on Line 8. If Line 7 is $500,000 and Line 8 is 20.000000%, Line 9 is $100,000. Round to whole dollars.
Edge case: a corporation with negative business income on Line 7 still apportions, producing a negative apportioned figure that flows into the NOL calculation.
The most common mistake is forgetting to apply the percentage and copying Line 7 to Line 9. The misconception is that Michigan corporations apportion only if they have out-of-state sales; every CIT filer apportions, even if the result is 100%.
Lines 10–11: Allocated Income
Lines 10 and 11 capture income that is not apportioned but allocated directly to Michigan, such as gain on the sale of Michigan real estate. Most filers enter 0 unless they sold Michigan property during the year.
Edge case: gain on the sale of intangibles is generally apportioned, not allocated. Only real estate and certain mineral interests are allocated.
The most common mistake is allocating ordinary business income that should have been apportioned. The misconception is that any Michigan-sourced income belongs on the allocation lines; only specifically identified items do.
Line 12: Total Michigan Income
Line 12 adds the apportioned income from Line 9 and the allocated income from Line 11. This is your total Michigan-source income before NOL deduction. The figure can be positive or negative.
Edge case: a corporation with a Michigan-only operation reports Line 9 equal to Line 7 and Line 11 equal to 0, so Line 12 equals Line 7.
The most common mistake is a transposition error between Lines 11 and 12. The misconception is that allocated and apportioned income are alternatives; they are added together, not substituted.
Line 13: Michigan Net Operating Loss Deduction
Line 13 deducts any Michigan NOL carryforward from prior years. Michigan NOLs carry forward 20 years and cannot be carried back, under MCL 206.623(4). Write the deduction as a positive number; the form subtracts it.
Edge case: NOLs created before 2012 under the old MBT do not transfer to the CIT. Only post-2011 CIT NOLs qualify.
The most common mistake is claiming a federal NOL instead of the Michigan-calculated NOL. The misconception is that the federal NOL automatically becomes a Michigan NOL; the two are computed separately.
Line 14: Michigan Taxable Income
Line 14 subtracts Line 13 from Line 12. This is the tax base. If the result is zero or negative, you owe no tax for the year but still must file.
Edge case: a corporation with negative Line 14 carries the loss forward and reports it on next year’s NOL schedule.
The most common mistake is forgetting to subtract Line 13 and treating Line 12 as the tax base. The misconception is that a zero tax base means no return is required; Treasury still requires the filing.
Line 15: Tax Before Credits
Line 15 multiplies Line 14 by 6%, the CIT rate set by MCL 206.623(1). A Line 14 of $100,000 produces a Line 15 of $6,000.
Edge case: the rate has not changed since 2012, but financial institutions on Form 4908 use a 0.29% franchise tax rate instead.
The most common mistake is using the personal income tax rate of 4.25% instead of the corporate rate of 6%. The misconception is that the corporate rate floats with the personal rate; it does not.
Line 16: Small Business Alternative Credit
Line 16 claims the Small Business Alternative Credit (SBAC), which reduces the tax to 1.8% of adjusted business income for qualifying small corporations. The credit phases out and disappears entirely if any single officer or shareholder takes more than $180,000 in compensation, or if allocated income exceeds $160,000.
Edge case: shareholders owning more than 5% are subject to the compensation test. Compensation includes wages and director fees.
The most common mistake is claiming the SBAC after a disqualifying bonus to a single officer. The misconception is that the credit is based on company size by employees; it is based on income and compensation tests under MCL 206.671.
Lines 17–22: Other Credits
Lines 17 through 22 capture other credits including the Renaissance Zone credit, the historic preservation credit, and brownfield credits. Each requires a separate certificate and supporting schedule.
Edge case: the historic preservation credit requires pre-approval from the State Historic Preservation Office before the project starts. Retroactive claims are denied.
The most common mistake is claiming a credit without the underlying certificate attached. The misconception is that credits are honored on the filer’s word; Treasury demands documentation.
Line 23: Total Credits
Line 23 sums Lines 16 through 22. The total cannot exceed Line 15; credits do not generate refunds for the CIT except where specifically refundable.
Edge case: the historic preservation credit is partially refundable; check Form 3581 instructions.
The most common mistake is treating a non-refundable credit as refundable. The misconception is that excess credits always carry forward; some, like Renaissance Zone credits, are use-it-or-lose-it.
Line 24: Tax After Credits
Line 24 subtracts Line 23 from Line 15. If the result is less than zero and the credits include a refundable portion, the refundable amount flows to Line 39.
Lines 25–37: Recapture and Surcharge Items
Lines 25 through 37 capture recapture of prior credits, surcharges on certain industries, and adjustments for short-period returns. Most filers enter 0 across these lines.
Edge case: a corporation that claimed a brownfield credit and later sold the property within five years must recapture the credit on Line 28.
The most common mistake is skipping these lines without confirming they apply. The misconception is that recapture only applies in audit; it is self-reported on this return.
Line 38: Estimated Payments and Prior-Year Overpayment
Line 38 totals all four quarterly estimated payments made with Form 4913 CIT Quarterly Voucher plus any prior-year overpayment credited forward. Cross-check against your MTO payment history.
Edge case: a payment made after the original due date counts toward late-payment interest, not toward Line 38 quarterly credit.
The most common mistake is including payments made for the prior tax year. The misconception is that estimated payments roll continuously; they are year-specific.
Lines 39–45: Balance Due, Refund, Interest, and Penalty
Lines 39 through 45 calculate the balance due or refund, plus interest and penalty if applicable. Interest accrues from the original due date at the rate published twice a year by Treasury under Revenue Administrative Bulletin 2025-12. The penalty starts at 5% and climbs to 25% for chronic non-filers.
The most common mistake is forgetting to add interest when filing late, which triggers a billing notice. The misconception is that filing an extension waives interest; Form 4 extends filing only, never payment.
Lines 46–47: Signature, Date, and Preparer Information
Line 46 requires the signature of a corporate officer — president, vice president, treasurer, or assistant treasurer. The date and title go on the lines beside the signature. Line 47 captures the paid preparer’s PTIN, name, and firm.
Edge case: a return signed by a bookkeeper without officer authority is treated as unsigned and rejected.
The most common mistake is missing the date next to the signature. The misconception is that an electronic signature on a paper return is acceptable; only an original ink signature works for paper filings.
Three Filled-Out Examples Using Real Scenarios
Scenario 1: Maria’s Michigan-Only Bakery (Small Business Alternative Credit)
Maria Lopez owns Sunrise Pastries Inc., a Michigan-only C corporation with $480,000 in gross receipts, $60,000 in federal taxable income, no out-of-state sales, and one officer paid $95,000.
| Form Section | What Maria Enters |
|---|---|
| Tax Year Dates | 01-01-2025 to 12-31-2025 |
| FEIN | 38-1234567 |
| Corporation Name | Sunrise Pastries Inc. |
| Line 1 — Federal Taxable Income | 60,000 |
| Line 7 — Business Income | 60,000 |
| Line 8 — Apportionment | 100.000000% |
| Line 14 — Michigan Taxable Income | 60,000 |
| Line 15 — Tax at 6% | 3,600 |
| Line 16 — SBAC | 2,520 |
| Line 24 — Tax After Credits | 1,080 |
| Line 38 — Estimated Payments | 1,200 |
| Line 40 — Refund | 120 |
Scenario 2: Marcus’s Multistate Manufacturer (Apportionment)
Marcus Chen runs Great Lakes Machining Corp., headquartered in Grand Rapids with $12 million in everywhere sales and $3 million in Michigan-destination sales. Federal taxable income is $400,000.
| Form Section | What Marcus Enters |
|---|---|
| Tax Year Dates | 01-01-2025 to 12-31-2025 |
| FEIN | 38-7654321 |
| Corporation Name | Great Lakes Machining Corp. |
| Line 1 — Federal Taxable Income | 400,000 |
| Line 4 — Taxes Add-back | 18,000 |
| Line 7 — Business Income | 418,000 |
| Line 8 — Apportionment | 25.000000% |
| Line 9 — Apportioned Income | 104,500 |
| Line 14 — Michigan Taxable Income | 104,500 |
| Line 15 — Tax at 6% | 6,270 |
| Line 38 — Estimated Payments | 6,000 |
| Line 39 — Balance Due | 270 |
Scenario 3: Aisha’s NOL Carryforward Filer
Aisha Robinson manages Pinecrest Logistics Inc., which lost $80,000 in 2023 and earned $120,000 in 2025. Pinecrest is Michigan-only with no other credits.
| Form Section | What Aisha Enters |
|---|---|
| Tax Year Dates | 01-01-2025 to 12-31-2025 |
| FEIN | 38-9876543 |
| Corporation Name | Pinecrest Logistics Inc. |
| Line 1 — Federal Taxable Income | 120,000 |
| Line 7 — Business Income | 120,000 |
| Line 8 — Apportionment | 100.000000% |
| Line 12 — Michigan Income | 120,000 |
| Line 13 — Michigan NOL | 80,000 |
| Line 14 — Michigan Taxable Income | 40,000 |
| Line 15 — Tax at 6% | 2,400 |
| Line 24 — Tax After Credits | 2,400 |
| Line 38 — Estimated Payments | 2,400 |
| Line 40 — Refund | 0 |
How to File the Completed Form
Michigan accepts MI-1120 through three channels: e-file software, MTO, and paper mail. The Treasury strongly prefers electronic filing because it cuts processing time from eight weeks to two weeks. Choose your channel before the due date so you have time to collect any rejected-return errors.
E-file through approved software. Programs like CCH Axcess, Drake, Lacerte, ProConnect, and UltraTax push the return through the Modernized e-File (MeF) system. There is no Treasury fee; the software vendor charges its own fee, typically $40 to $80 per state return. Payment can be drawn from the corporation’s checking account via direct debit or paid separately through MTO with ACH or credit card. Processing time is two to three weeks. Keep the software’s electronic acknowledgment as your proof of filing.
File through Michigan Treasury Online. Log in at the MTO portal and select Corporate Income Tax. The system walks you through each line and posts payment instantly. ACH debit is free; credit card payments carry a 2.3% convenience fee charged by the card processor. Processing time is two weeks, and the MTO confirmation number is your proof of filing.
File by paper mail. Print the completed Form 4891, sign in ink, and mail with any required schedules to Michigan Department of Treasury, P.O. Box 30803, Lansing, MI 48909 for returns with payment, or P.O. Box 30804, Lansing, MI 48909 for refund returns. There is no filing fee, but Treasury recommends certified mail with return receipt because the postmark date governs timeliness. Processing time is six to eight weeks. The certified-mail green card is your proof of filing.
The return is due on the last day of the fourth month after the tax year ends. Calendar-year filers face an April 30 deadline. An automatic extension to file is available by submitting Form 4 Application for Extension by the original due date, which extends filing by six months but does not extend payment.
What Happens After You File
Treasury logs the return within 72 hours for e-filed returns and within two weeks for paper returns. You can check status at MTO Inquiry. The system shows received, processing, or completed.
If the return is complete and the math agrees with federal records, Treasury issues any refund within two weeks of e-file or eight weeks of paper. Refunds under $100 are paid by paper check; larger refunds default to direct deposit if account information was entered.
If Treasury finds an error, the corporation receives a Notice of Adjustment within 90 days. You have 60 days to dispute or pay. Disputes go through an informal conference under MCL 205.21, with appeal rights to the Michigan Tax Tribunal.
Audits, when they happen, are usually triggered by a federal IRS audit or by a sales factor that differs materially from the prior year. Michigan’s statute of limitations is four years from the later of the due date or the date filed, under MCL 205.27a. Keep records for at least four years after filing.
Mistakes to Avoid When Filling Out the Form
- Using the prior year’s form. Treasury rejects forms with the wrong revision date, delaying filing past the deadline.
- Skipping the FEIN dash. A missing or misplaced dash kicks the return into the manual-review queue.
- Forgetting to add back state income taxes on Line 4. This understates Michigan income and triggers an automatic adjustment with interest.
- Using a three-factor apportionment formula. The CIT uses only the sales factor, and a three-factor calculation produces a tax notice within 90 days.
- Claiming the federal NOL on Line 13. Michigan NOLs are computed separately; using the federal NOL causes a denial of the deduction.
- Missing the Small Business Alternative Credit’s officer compensation cap. Paying any officer more than $180,000 disqualifies the credit entirely.
- Failing to attach the SBAC worksheet (Form 4893). Treasury denies the credit without the supporting schedule.
- Mailing the return to the wrong P.O. Box. Payment returns and refund returns use different boxes, and misrouting adds weeks of processing.
- Leaving Line 47 preparer information blank. Paid preparers face a $50 per-return penalty under MCL 205.24a.
- Filing an extension and assuming payment is also extended. Form 4 extends only filing; unpaid tax accrues interest from the original due date.
- Reporting cents instead of whole dollars. Treasury’s scanner reads decimals as additional digits, producing absurd assessment notices.
- Forgetting to sign the paper return. Unsigned returns are treated as never filed.
Do’s and Don’ts
Do: – Do download the form fresh each year from the Michigan Treasury CIT Forms page, because revisions change line numbers. – Do file electronically when possible, because e-file processing takes one-fourth the time of paper. – Do reconcile Line 1 to federal Form 1120, Line 28, line by line before submitting. – Do pay the balance due by the original due date, because interest runs from that date regardless of extensions. – Do keep all supporting workpapers for at least four years, because the audit window runs four years from filing. – Do verify your SBAC eligibility against the $180,000 compensation cap before claiming the credit, because a single bonus can disqualify it.
Don’t: – Don’t paraphrase line labels in your software, because Treasury matches the exact form field names. – Don’t carry forward MBT-era NOLs to the CIT, because they do not transfer under the 2012 statute change. – Don’t sign the return as a non-officer, because Treasury treats it as unsigned. – Don’t round the apportionment percentage to fewer than six decimals, because Treasury recalculates and assesses for rounding errors. – Don’t pay by personal check from a non-corporate account, because the payment may not post to the corporate FEIN. – Don’t ignore a Notice of Adjustment past 60 days, because dispute rights lapse and the assessment becomes final.
Pros and Cons of Filing on Your Own vs. With Help
Pros of filing on your own: – No professional fees, saving $500 to $2,500 for a small C corporation. – Faster turnaround if your records are clean and your federal return is finished. – Full understanding of your own tax position, which helps planning for next year. – Direct relationship with Treasury, with no intermediary slowing notices. – MTO and modern software make the mechanics manageable for a careful filer.
Cons of filing on your own: – Apportionment rules are technical, and errors compound across multiple states. – The SBAC’s compensation and income tests are easy to misread, costing thousands. – NOL tracking requires its own schedule that many filers neglect. – Audit risk is the same, but you lack a representative to respond on your behalf. – Treasury notices are written in technical language and can be hard to interpret without help.
FAQs
Do I file MI-1120 if my corporation had no Michigan sales but is registered in Michigan?
Yes. A corporation registered in Michigan with physical presence must file even with zero apportioned income, because nexus is independent of sales volume.
Can I file MI-1120 jointly with my federal Form 1120 through the IRS?
No. Michigan accepts MI-1120 only through Michigan Treasury Online or approved state e-file software, never bundled with IRS submissions.
Is the Corporate Income Tax rate still 6% for tax year 2025?
Yes. The CIT rate has been a flat 6% of apportioned business income since 2012 under MCL 206.623(1), with no scheduled change.
Do I write my DBA name in the Corporation Name box?
No. Use the legal name on the IRS CP 575 letter that issued the FEIN; a DBA causes a name-mismatch notice.
Should officer compensation appear on Line 4 of MI-1120?
No. Officer compensation is reported on the SBAC worksheet (Form 4893), not on the add-back lines of the main return.
Do I have to file if my gross receipts are under $350,000?
No. A corporation with apportioned gross receipts below $350,000 is exempt from filing under MCL 206.621, unless it owes recapture tax.
Can I carry a federal NOL back to a prior Michigan CIT year?
No. Michigan NOLs cannot be carried back at all; they only carry forward up to 20 years under MCL 206.623(4).
Is an extension on Form 4 also an extension to pay?
No. Form 4 extends filing by six months but never extends payment, and interest accrues from the original April 30 due date.
Do I include cents on Line 15 if my tax is $6,270.42?
No. All entries are whole dollars rounded; 6,270 is correct on Line 15.
Should I attach a copy of my federal Form 1120 to MI-1120?
Yes. Treasury requires federal Form 1120, pages 1 through 5, plus any Schedule M-3, attached to support Line 1.
Can a single-member LLC file MI-1120?
No. A single-member LLC defaulting to disregarded status does not file MI-1120; the owner reports on their personal return instead.
Do I sign Form 4891 if I am the corporate bookkeeper, not an officer?
No. Only a corporate officer — president, vice president, treasurer, or assistant treasurer — may sign; a bookkeeper signature renders the return unsigned.
Should I use the apportionment percentage from my federal state allocation if it is already calculated?
No. Michigan uses a destination-based single sales factor, which often differs from federal state allocations; recalculate using Michigan rules.
Can I e-file an amended MI-1120?
Yes. Amended CIT returns can be filed through MTO or approved software by checking the Amended Return box at the top of Form 4891.
Related reading
- How to Fill Out Michigan Form MI-1040 (w/Examples) + FAQs
- How to Fill Out Michigan Form MI-1040X-12 (w/Examples) + FAQs
- How to Fill Out Michigan Form MI-1065 (w/Examples) + FAQs
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