EX-23.1 5 ny20001148x2_ex23-1.htm EXHIBIT 23.1

Exhibit 23.1
Consent of Independent Registered Public Accounting Firm
We consent to the incorporation by reference in this Pre-Effective Amendment No. 1 to the Registration Statement on Form S-4 (No. 333-260771) of First Interstate BancSystem, Inc. of our reports dated February 26, 2021, relating to our audits of the consolidated financial statements and the effectiveness of internal control over financial reporting of First Interstate BancSystem, Inc., appearing in the Annual Report on Form 10-K of First Interstate BancSystem, Inc. for the year ended December 31, 2020.
We also consent to the reference to our firm under the heading "Experts" in the Proxy Statement/Prospectus, which is part of this Registration Statement.
/s/ RSM US LLP
Des Moines, Iowa
December 14, 2021