Exhibit 99.1

JOINT FILING AGREEMENT

The undersigned hereby agree that this Schedule 13D, dated February 23, 2021, with respect to the Common Stock, par value $0.01 per share, of Southern National Bancorp of Virginia, Inc., a Virginia corporation, is, and any amendments hereto signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.

Dated: February 23, 2021

CASTLE CREEK CAPITAL PARTNERS IV, LP
By:	/s/ John M. Eggemeyer
Name:	John M. Eggemeyer
Title:	Managing Principal

CASTLE CREEK CAPITAL IV, LLC
By:	/s/ John M. Eggemeyer
Name:	John M. Eggemeyer
Title:	Managing Principal

CASTLE CREEK CAPITAL PARTNERS VII, LP
By:	/s/ John M. Eggemeyer
Name:	John M. Eggemeyer
Title:	Managing Principal

CASTLE CREEK CAPITAL VII LLC
By:	/s/ John M. Eggemeyer
Name:	John M. Eggemeyer
Title:	Managing Principal

SIGNATURE PAGE TO JOINT FILING AGREEMENT (SOUTHERN NATIONAL BANCORP OF VIRGINIA, INC.)