UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (date of earliest event reported): March 14, 2023

Mercantile Bank Corporation

(Exact name of registrant as specified in its charter)

Michigan	000-26719	38-3360865
(State or other jurisdiction	(Commission File	(IRS Employer
of incorporation)	Number)	Identification Number)

310 Leonard Street NW, Grand Rapids, Michigan	49504
(Address of principal executive offices)	(Zip Code)
Registrant's telephone number, including area code	616-406-3000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock	MBWM	The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).                                                                Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.          ☐

Item 4.01         Changes in Registrant’s Certifying Accountant.

On March 14, 2023, the Audit Committee of the Board of Directors of Mercantile Bank Corporation (the “Company”, "our", "we", "us") concluded its proposal for selection of an independent registered public accounting firm for 2023, and appointed Plante & Moran, PLLC (“Plante & Moran”) as our independent registered public accounting firm for the fiscal year ending December 31, 2023, subject to normal and customary client engagement procedures. On the same date, the Audit Committee dismissed BDO USA, LLP (“BDO”) as our independent registered public accounting firm.

The reports of BDO on our consolidated financial statements as of and for the fiscal years ended December 31, 2022 and 2021 did not contain an adverse opinion or a disclaimer of opinion, and were not qualified or modified as to uncertainty, audit scope, or accounting principles.

During the fiscal years ended December 31, 2022 and 2021, and the subsequent interim period from January 1, 2023 through March 14, 2023, there were (i) no disagreements within the meaning of Item 304(a)(1)(iv) of Regulation S-K between us and BDO on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which disagreements, if not resolved to BDO’s satisfaction would have caused it to make reference to the subject matter of such disagreements in connection with its reports on our consolidated financial statements for such years; and (ii) no “reportable events” within the meaning of Item 304(a)(1)(v) of Regulation S-K.

The Company provided BDO with a copy of the disclosures that the Company is making in response to Item 4.01 on this Current Report on Form 8-K, and requested that BDO furnish it with a letter addressed to the Securities and Exchange Commission stating whether it agrees with the above statements. A copy of BDO’s letter, dated March 15, 2023 regarding the above disclosures is filed as Exhibit 16 to this report.

During the fiscal years ended December 31, 2022 and 2021, and the subsequent interim period from January 1, 2023 through March 14, 2023, neither we nor anyone on our behalf consulted with Plante & Moran regarding either (i) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered with respect to our consolidated financial statements, in any case where a written report or oral advice was provided to us by Plante & Moran that Plante & Moran concluded was an important factor considered by us in reaching a decision as to any accounting, auditing, or financial reporting issue; or (ii) any matter that was the subject of a “disagreement” within the meaning of Item 304(a)(1)(iv) of Regulation S-K or a “reportable event” within the meaning of Item 304(a)(1)(v) of Regulation S-K.

Item 9.01     Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number  Description

16	Letter to Securities and Exchange Commission from BDO USA, LLP
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

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Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Mercantile Bank Corporation
By:	/s/ Charles E. Christmas
	Executive Vice President, Chief
	Financial Officer and Treasurer

Date: March 16, 2023

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Exhibit Index

Exhibit Number  Description

16	Letter to Securities and Exchange Commission from BDO USA, LLP
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)