    <SEC-DOCUMENT>0001140361-21-012372-index.html : 20210412
    <SEC-HEADER>0001140361-21-012372.hdr.sgml : 20210412
    <ACCEPTANCE-DATETIME>20210412090559
    ACCESSION NUMBER:		0001140361-21-012372
    CONFORMED SUBMISSION TYPE:	DEFA14A
    PUBLIC DOCUMENT COUNT:		3
    FILED AS OF DATE:		20210412
    DATE AS OF CHANGE:		20210412

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			COLUMBIA BANKING SYSTEM, INC.
    		CENTRAL INDEX KEY:			0000887343
    		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
    		IRS NUMBER:				911422237
    		STATE OF INCORPORATION:			WA
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		DEFA14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-20288
    		FILM NUMBER:		21819541

    	BUSINESS ADDRESS:
    		STREET 1:		1301 A STREET
    		CITY:			TACOMA
    		STATE:			WA
    		ZIP:			98402
    		BUSINESS PHONE:		2533051900

    	MAIL ADDRESS:
    		STREET 1:		1301 A STREET
    		CITY:			TACOMA
    		STATE:			WA
    		ZIP:			98402

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COLUMBIA BANKING SYSTEM INC
    		DATE OF NAME CHANGE:	19930328
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>DEFA14A
    <SEQUENCE>1
    <FILENAME>nc10022254x2_defa14a.htm
    <DESCRIPTION>DEFA14A
    <TEXT>
    Document 1 - file: nc10022254x2_defa14a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>2
    <FILENAME>nc10022254x2_nc1.jpg
    <TEXT>
    Document 2 - file: nc10022254x2_nc1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>nc10022254x2_nc2.jpg
    <TEXT>
    Document 3 - file: nc10022254x2_nc2.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>