Key takeaways
- The Michigan state rate is 6% of gross proceeds, and the seller does not choose its own filing frequency.
- Monthly returns and payments are due on or before the 20th, and a due date on a weekend or holiday moves to the next business day.
- A marketplace facilitator remits the tax on the sales it facilitates, so the seller generally leaves those sales off its own return.
- Every filer also submits the annual return by February 28, and for 2026 sales that date is March 1, 2027.
The 6% rate and when a sale belongs on the return
MCL 205.52 sets the Michigan sales tax at 6% of gross proceeds. Apply the rate to the taxable portion of each sale, and keep an exemption certificate for each exempt customer.
Worked example: a taxable sale of $1,000 made in October 2026 carries $60 of tax, which is 6% of $1,000. Tax accrues on the last day of the month in which the sale is incurred, so the sale belongs on the October 2026 return even if the customer pays in November. The rule is in MCL 205.56(3), and it matters most for sales on account.
Split mixed invoices before you compute the tax. An invoice with a $300 exempt item and a $700 taxable item has a $700 taxable base and $42 of tax. Putting the whole $1,000 into the base overstates the return by $18.
How Treasury sets the filing frequency
Treasury determines how often a business must file based on its previous tax due. Every October, Treasury mails letters to businesses that will file more or less often beginning January 1, and copies of those letters are available in MTO. Treasury's December 2025 bulletin says the frequency determination cannot be changed, so a client cannot choose a quarterly schedule to save effort.
Decision rule: in November, log in to MTO for each Michigan seller and find the October letter. If it assigns monthly filing, put the 20th of each month on the calendar. If it assigns quarterly or annual filing, use the due dates shown on the account and do not count three months forward from last year. If the business is new and has no letter yet, read the frequency shown on the account before the first period closes.
Failure mode: a client keeps filing on last year's calendar after Treasury moves the account to a different frequency. The return then goes in on the wrong date and the team misses the real one. Fix: store each October letter in the client file and update the calendar the same week it arrives.
Due dates for monthly filers in 2026 and early 2027
MCL 205.56(1) requires the seller to make out a return for the preceding month and transmit it with the remittance on or before the 20th day of each month. The return and payment for October 2026 sales are therefore due Friday, November 20, 2026.
The weekend rule is in MCL 205.56(6): if a due date falls on a Saturday, Sunday, state holiday or legal banking holiday, the tax is due on the next succeeding business day. The return for November 2026 sales is due December 20, 2026, which is a Sunday, so it moves to Monday, December 21, 2026.
The return for December 2026 sales is due Wednesday, January 20, 2027. Put all three dates on the firm calendar with an internal target two business days early, so that the first time anyone opens the return is not the day it is due.
Quarterly filers and the schedule Treasury sets
MCL 205.56(4) allows the department to require filing of returns and payment of the tax for other than monthly periods. That is the basis for quarterly and annual schedules.
The statute text checked for this guide does not state a quarterly due day. Take the quarterly due dates from the MTO account for each client, and do not build them from a generic calendar or from another state's schedule.
The annual return and the February 28 deadline
Treasury's December 2025 bulletin says the Sales, Use and Withholding (SUW) annual return is due for all filers on February 28, 2026. A 2023 Treasury bulletin says all business taxpayers must submit the annual return by February 28. Monthly and quarterly filers are included.
For the return covering 2026, February 28, 2027 is a Sunday. Under MCL 205.56(6), the due date moves to Monday, March 1, 2027. Do not plan to that date. Plan to have the figures reconciled by the Friday before February 28, 2027, so the client can review the number before the weekend.
Failure mode: the annual return is missed because every monthly return was filed on time and the team treats the year as closed. Fix: a separate February calendar entry for each Michigan account, with the annual total reconciled to the twelve monthly returns, or to the quarterly returns, before anything is filed.
Filing and paying on Michigan Treasury Online
Michigan Treasury Online is where the business files and pays its SUW returns, and where the frequency letters and account due dates are kept. Treasury describes it as the place to file returns and pay business taxes.
For each period, take gross sales and taxable sales from the sales ledger, not from bank deposits, and confirm that the tax equals 6% of the taxable base before you submit. Bank deposits pick up marketplace payouts, refunds and customer prepayments that do not match the return, so a deposit-based return is hard to defend.
Under MCL 205.56(2), a larger taxpayer must remit by an electronic funds transfer method approved by the department. Set up the payment method before the due date rather than on it.
Marketplace facilitators decide which sales the seller reports
MCL 205.52d(1) requires a marketplace facilitator to remit sales tax on taxable sales it makes or facilitates for marketplace sellers to Michigan purchasers, regardless of whether the marketplace seller has nexus in Michigan. The provision took effect January 1, 2020.
Under MCL 205.52d(9), a marketplace seller is not liable for the tax imposed on sales made through a marketplace facilitator, unless the seller fails to provide the facilitator with sufficient information. That protection is why those sales should not be on the seller's own return.
Decision rule: split each client's sales into two channels. Sales through a facilitator go on the marketplace report. Sales through the client's own website, phone orders, trade shows or direct invoices go on the Michigan return at 6%. Ask for gross sales by channel for each month, and do not net one channel against the other.
Worked example: a seller records $40,000 of Michigan sales in October 2026, with $25,000 direct and $15,000 through a facilitator. The return reports $25,000 of taxable sales and $1,500 of tax, which is 6% of $25,000. The $15,000 is the facilitator's to remit. If the seller did not give the facilitator sufficient information, the protection may not apply, so confirm with the client that the marketplace has the correct details on file.
Failure mode: the same marketplace sales appear on the facilitator report and on the client's own return, which doubles the base. Fix: each month, reconcile the marketplace totals to the return and record which sales were excluded and why.
What to send the client before the first Michigan return
Before the first period closes, confirm the account and the filing frequency for each Michigan seller in MTO. Write the frequency and the next three due dates into the client file so the team is working from the same schedule.
Set up the sales ledger with three fields for every sale: the channel (direct or marketplace), whether the sale is taxable or exempt, and the month the sale was incurred. Those fields make the monthly reconciliation a filter rather than a rebuild.
Client wording for the frequency check: “Please log in to your Michigan Treasury Online account this month and send me any filing frequency letter from October 2026, so I can confirm whether your sales tax returns are monthly, quarterly or annual.” Ask for the reply within two business days.
Client wording for the marketplace split: “For each marketplace you sell through, please send the monthly gross sales report and the name of the marketplace. Keep sales from your own website separate, and tell me if any marketplace does not have your correct business details.” Ask them to confirm by email.