First Internet Bancorp

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934

Filed by the Registrantþ

Filed by a Party other than the Registranto

Check the appropriate box:

First Internet Bancorp

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

March 27, 2025

DEAR FELLOW SHAREHOLDER,

It is my pleasure to invite you to attend the 2025 Annual Meeting of Shareholders of First Internet Bancorp on Monday, May 19, 2025 at 1:00 p.m. Eastern Time, which will be hosted virtually via the Internet at www.virtualshareholdermeeting.com/INBK2025. At the meeting, you will be able to vote your shares electronically on the business items listed in the notice of the meeting and submit your questions.

We are again furnishing our proxy materials to our shareholders primarily over the Internet. We believe that this e-proxy process expedites shareholders’ receipt of proxy materials, helps keep our costs low and reduces the environmental impact of our annual meeting. On or about March 27, 2025, a Notice of Internet Availability of Proxy Materials will be mailed to our shareholders containing instructions on how to access our proxy statement, annual report and any related materials and how to vote online. The Notice of Internet Availability of Proxy Materials also contains instructions on how you can elect to receive a paper copy of the proxy statement, annual report and any related materials.

WHETHER OR NOT YOU PLAN TO ATTEND THE MEETING,

YOUR VOTE IS IMPORTANT. PLEASE VOTE PROMPTLY.

You may vote your shares via a toll-free telephone number or over the Internet. If you receive a paper copy of the proxy card by mail, you may sign, date and mail the proxy card in the envelope provided. Instructions regarding available methods of voting are contained in the Notice of Internet Availability of Proxy Materials, the proxy statement and the proxy card. If you attend the meeting, you may vote electronically, provided that you comply with the requirements summarized in the proxy statement.

Sincerely,

DAVID B. BECKER

Chairman and Chief Executive Officer

8701 E. 116th Street, Fishers, Indiana 46038 • (317) 532-7900

NOTICE OFANNUAL MEETING OF SHAREHOLDERS

To Be Held May 19, 2025

The 2025 Annual Meeting of Shareholders of First Internet Bancorp will be held virtually via the Internet at www.virtualshareholdermeeting.com/INBK2025, at 1:00 p.m. Eastern Time on Monday, May 19, 2025, for the following purposes:

•To elect eight directors to serve until the next annual meeting of shareholders;

•To approve, in an advisory (non-binding) vote, the compensation paid to our named executive officers;

•To determine, in an advisory (non-binding) vote, whether to conduct future advisory votes to approve executive compensation every one, two or three years;

•To ratify the appointment of Forvis Mazars, LLP as our independent registered public accounting firm for 2025; and

•To transact such other business as may properly come before the meeting or any adjournments thereof.

Only shareholders of record as of the close of business on March 21, 2025 are entitled to notice of and to vote at the annual meeting or any adjournments thereof. In the event there are not sufficient votes for approval of one or more of the above matters at the time of the annual meeting, the annual meeting may be adjourned in order to permit further solicitation of proxies.

Important Notice Regarding the Availability of Proxy Materials for theAnnual Meeting of Shareholders to be Held May 19, 2025

Copies of the notice of annual meeting of shareholders, this proxy statement and the 2024 annual report are each available at www.firstinternetbancorp.com.

Your vote is important, regardless of the number of shares you own. If you do not attend the meeting to vote electronically, your vote will not be counted unless a proxy representing your shares is voted at the meeting. To ensure that your shares will be voted at the meeting, please vote in one of these ways:

•Go to the website noted on your proxy card or the Notice of Internet Availability of Proxy Materials and vote via the Internet;

•If you receive a printed copy of the proxy materials by mail, use the toll-free telephone number shown on your proxy card;

•If you receive a printed copy of the proxy materials by mail, mark, sign, date and promptly return your proxy card in the envelope provided, which requires no additional postage if mailed in the U.S.; and

•If you attend the meeting, you may revoke any previously-submitted proxy and vote electronically.

By order of the Board of Directors,

President, Chief Operating Officer and Corporate Secretary

Fishers, Indiana

March 27, 2025

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

The statements included in this proxy statement, including in the section entitled “EXECUTIVE COMPENSATION—Compensation Discussion and Analysis—Business Highlights”, regarding future financial performance, results of operations, expectations, plans, strategies, goals, priorities and other statements that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements are based upon current beliefs, expectations and assumptions and are subject to significant risks, uncertainties and changes in circumstances that could cause actual results to differ materially from the forward-looking statements. A detailed discussion of risks, uncertainties and changes in circumstances that could cause actual results and events to differ materially from such forward-looking statements is included in the section titled “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2024. Readers of this proxy statement are cautioned not to rely on these forward-looking statements, since there can be no assurance that these forward-looking statements will prove to be accurate. To the extent permitted by applicable law, we expressly disclaim any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.