SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

o

Rule 13d-1(b)

o

Rule 13d-1(c)

x

Rule 13d-1(d)

CUSIP No. 598511103

1.

Names of Reporting Persons
John S. Koza

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

x

3.

SEC Use Only

4.

Citizenship or Place of Organization
United States

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
822,400

6.

Shared Voting Power
0

7.

Sole Dispositive Power
822,400

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
822,400

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
6.7%

12.

Type of Reporting Person (See Instructions)
IN

CUSIP No. 598511103

1.

Names of Reporting Persons
Patricia C. Koza

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

x

3.

SEC Use Only

4.

Citizenship or Place of Organization
United States

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
60,325

6.

Shared Voting Power
0

7.

Sole Dispositive Power
60,325

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person:
60,325

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
0.5%

12.

Type of Reporting Person (See Instructions)
IN

Item 1.

(a)

Name of Issuer
MidWestOne Financial Group, Inc.

(b)

Address of Issuer’s Principal Executive Offices
102 South Clinton St.

Iowa City, IA 52240

Item 2.

(a)

Name of Person Filing
(i)                                   John S. Koza

(ii)                                Patricia C. Koza

(b)

Address of Principal Business Office or, if none, Residence
(i)                                   The address for John S. Koza is:

c/o MidWestOne Financial Group, Inc.

102 South Clinton St.

Iowa City, IA 52240

(ii)                                The address for Patricia C. Koza is:

c/o MidWestOne Financial Group, Inc.

102 South Clinton St.

Iowa City, IA 52240

(c)

Citizenship
(i)                                   John S. Koza – United States

(ii)                                Patricia C. Koza – United States

(d)

Title of Class of Securities
Common Stock, par value $1.00 per share

(e)

CUSIP Number
598511103

Item 3.

If this statement is filed pursuant to §§240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)

o

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act (15 U.S.C. 80a-3);

(j)

o

A non-U.S. institution in accordance with § 240.13d–1(b)(1)(ii)(J);

(k)

o

Group, in accordance with § 240.13d–1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with § 240.13d–1(b)(1)(ii)(J), please specify the type of institution: Not applicable

Item 4.

Ownership

(a)

Amount beneficially owned:   

John S. Koza – 822,400 shares*

Patricia C. Koza – 60,325 shares**

*Comprised of shares held as follows: (i) 202,840 shares of Common Stock beneficially owned by Mr. Koza individually and over which Mr. Koza holds sole investment and voting power; and (ii) 619,560 shares of Common Stock held in various family trust accounts, over which Mr. Koza holds sole investment and voting power.  In accordance with Rule 13d-4, Mr. Koza disclaims beneficial ownership of the shares of Common Stock beneficially owned by Ms. Koza described below.

** Comprised of 60,325 shares of Common Stock beneficially owned by Ms. Koza individually and over which Ms. Koza holds sole investment and voting power.  In accordance with Rule 13d-4, Ms. Koza disclaims beneficial ownership of the shares of Common Stock beneficially owned by Mr. Koza described above.

(b)

Percent of class:   

John S. Koza – 6.7%†

Patricia C. Koza – 0.5%†

†The applicable percentage ownership for each Reporting Person is based upon 12,219,611 shares of Common Stock outstanding as of December 31, 2017.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote:

Please see Row 5 on the cover page hereto for each Reporting Person, as well as the notes to Item 4(a) above, which such information is hereby incorporated by reference into this Item 4(c)(i).

(ii)

Shared power to vote or to direct the vote:

Please see Row 6 on the cover page hereto for each Reporting Person, as well as the notes to Item 4(a) above, which such information is hereby incorporated by reference into this Item 4(c)(ii).

(iii)

Sole power to dispose or to direct the disposition of:

Please see Row 7 on the cover page hereto for each Reporting Person, as well as the notes to Item 4(a) above, which such information is hereby incorporated by reference into this Item 4(c)(iii).

(iv)

Shared power to dispose or to direct the disposition of:

Please see Row 8 on the cover page hereto for each Reporting Person, as well as the notes to Item 4(a) above, which such information is hereby incorporated by reference into this Item 4(c)(iv).

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following:   o

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Not Applicable.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Not Applicable.

Item 8.

Identification and Classification of Members of the Group

Not Applicable.

Item 9.

Notice of Dissolution of Group

Not Applicable.

Item 10.

Certifications

Not Applicable.

Date: January 29, 2018

/s/ John S. Koza by Patricia C. Koza POA

John S. Koza

/s/ Patricia C. Koza

Patricia C. Koza

/s/ John S. Koza by Patricia C. Koza POA

John S. Koza

/s/ Patricia C. Koza

Patricia C. Koza