Exhibit 8.1 

LUSE GORMAN, PC

ATTORNEYS AT LAW

5335 WISCONSIN AVENUE, N.W., SUITE 780

WASHINGTON, D.C. 20015

TELEPHONE (202) 274-2000

FACSIMILE (202) 362-2902

www.luselaw.com

April 15, 2026

Board of Directors

Esquire Financial Holdings, Inc.

100 Jericho Quadrangle, Suite 100

Jericho, NY 11753

Ladies and Gentlemen:

We have acted as special counsel to Esquire Financial Holdings, Inc., a Maryland corporation (“Esquire”), in connection with the transactions described in the Agreement and Plan of Merger, dated as of March 11, 2026 (the “Merger Agreement”), by and among Esquire, Signature Bancorporation, Inc., an Illinois corporation (“Signature”), and Esquire Merger Sub, Inc. a Maryland corporation and a wholly owned subsidiary of Esquire (“Merger Sub”), pursuant to which Merger Sub will merge with and into Signature, with Signature remaining as the surviving corporation (the “Merger”), and as soon as reasonably practicable following the Merger and as part of a single integrated transaction for purposes of the Internal Revenue Code of 1986, as amended, Signature will merge with and into Esquire (the “Second Step Merger”, and together with the Merger, the “Mergers”), with Esquire remaining as the surviving corporation in the Second Step Merger. At your request, and in connection with the preparation and filing of the related Registration Statement on Form S-4, which includes the Joint Proxy Statement/Prospectus (the “Proxy Statement/Prospectus”), as initially filed by Esquire with the U.S. Securities and Exchange Commission on April 15, 2026 (the “Registration Statement”), we are providing this opinion.

In connection with this opinion, we have reviewed: (i) the Merger Agreement; (ii) the Registration Statement; and (iii) the Proxy Statement/Prospectus. We have not, however, undertaken any independent investigation of any factual matter set forth in any of the foregoing. For purposes of this opinion, we have assumed, with your permission, (i) that the Mergers will be consummated in the manner described in Merger Agreement and the Registration Statement, and (ii) the statements concerning the Mergers set forth in the Merger Agreement and the Registration Statement are true and complete and will remain true and complete at all times up to and including the Effective Time (as defined in the Merger Agreement). We have also assumed that the parties have complied with, and will continue to comply with, the obligations, covenants and agreements contained in the Merger Agreement.

We have participated in the preparation of the discussion set forth in the section entitled “MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER” in the Registration Statement. Based on the foregoing and subject to the qualifications, assumptions and limitations stated herein and in the Registration Statement, it is our opinion that such discussion of those consequences, insofar as it summarizes United States federal income tax law, is accurate in all material respects.

Esquire Financial Holdings, Inc.

April 15, 2026

Page 2

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the references to us in the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended.