SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

(Mark One)

For the fiscal year ended December 31, 2013

OR

For the transition period from __________ to __________

Commission file number 0-26128

NorthWest Indiana Bancorp

(Exact name of registrant as specified in its charter)

(219) 836-4400

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act: None

Securities registered pursuant to Section 12(g) of the Act: Common Stock, without par value

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ¨ No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ¨ No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).          Yes x         No £

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of Registrant’s knowledge in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. £

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ¨ No x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act:

Large accelerated filer: ¨ Accelerated filer: ¨ Non-Accelerated filer: ¨ Smaller reporting company x

(Do not check if a smaller reporting company)

Based on the average bid and ask prices for the registrant’s Common Stock at June 30, 2013, at that date, the aggregate market value of the registrant’s Common Stock held by nonaffiliates of the registrant (assuming solely for the purposes of this calculation that all directors and executive officers of the registrant are “affiliates”) was $53,067,428.

There were 2,841,164 shares of the registrant’s Common Stock, without par value, outstanding at January 31, 2014.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the following documents have been incorporated by reference into this Annual Report on Form 10-K:

1. 2013 Annual Report to Shareholders. (Part II)

2. Definitive Proxy Statement for the 2014 Annual Meeting of Shareholders. (Part III)

Explanatory Note

This amendment is filed solely to amend the Consent of Independent Registered Public Accounting Firm which was filed as Exhibit 23.1 to NorthWest Indiana Bancorp’s Annual Report on Form 10-K for the year ended December 31, 2013. That exhibit, as originally filed, inadvertently stated the consent date as February 15, 2014. The revised exhibit being filed herewith now states the correct date of February 25, 2014. No revisions have been made to the financial statements or any other disclosures contained in the Annual Report.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: February 28, 2014

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on February 25, 2014:

EXHIBIT INDEX