UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No.     )

Filed by the Registrant  ☒

Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐   Preliminary Proxy Statement	☐   Confidential, for Use of the Commission Only          (as permitted by Rule 14a-6(e)(2))
☐   Definitive Proxy Statement
☒   Definitive Additional Materials
☐   Soliciting Material under §240.14a-12

AVISTA CORPORATION

(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 the appropriate box):

☒ No fee required.

☐ Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1) Title of each class of securities to which the transaction applies:

(2) Aggregate number of securities to which the transaction applies:

(3) Per unit price or other underlying value of the transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4) Proposed maximum aggregate value of the transaction:

(5) Total fee paid:

☐ Fee paid previously with preliminary materials.

☐ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

(1) Amount Previously Paid:

(2) Form, Schedule or Registration Statement No.:

(3) Filing Party:

(4) Date Filed:

*** Exercise Your Right to Vote *** Important Notice Regarding the Availability byVirtual Meeting of Proxy Materials for the Shareholder Meeting to Be Held on Monday, May 11, 2020. Meeting Information AVISTA CORP. Meeting Type: Annual Meeting For holders as of: March 10, 2020 Date: May 11, 2020 Time: 8:15 AM PDT Location: Meeting live via the Internet-please visit www.virtualshareholdermeeting.com/AVA2020. This year’s Annual Meeting will be a completely “virtual meeting” of shareholders. You will be able to attend the Annual Meeting, vote and submit questions during the Annual Meeting via the live webcast by visiting (www.virtualshareholdermeeting.com/AVA2020). AVISTA CORP. You are receiving this communication because you hold shares in P.O. BOX 3727 the company named above. SPOKANE, WA 99220-3727 This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. P33771 proxy See the materials reverse and side voting of this instructions. notice to obtain D03433 -

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: NOTICE AND PROXY STATEMENT ANNUAL REPORT How to View Online: Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX XXXX (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow XXXX XXXX XXXX XXXX (located on the following page) in the subject line. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before April 27, 2020 to facilitate timely delivery. How To Vote Please Choose One of the Following Voting Methods Vote By Internet: Before The Meeting: Go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow P33771 XXXX XXXX XXXX XXXX (located on the following page) available and follow the instructions. - During The Meeting: Go to www.virtualshareholdermeeting.com/AVA2020. Have the information that is printed in the box marked by D03434 the arrow XXXX XXXX XXXX XXXX (located on the following page) available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.

Voting Items The Board of Directors recommends you vote FOR The Board of Directors recommends you vote FOR the following: proposals 2 and 3. 1. Election of Directors Nominees: 2. R a t i f i c a t i o n o f t h e a p p o i n t m e n t o f Deloitte & Touche LLP as the Company’s 1a. Kristianne Blake independent registered public accounting firm for 2020. 1b. Donald C. Burke 3. Advisory (non-binding) vote on executive compensation. 1c. Rebecca A. Klein NOTE: The proxies will have discretionary authority to 1d. Scott H. Maw transact such other business as may come before the meeting or any adjournment or postponement thereof. 1e. Scott L. Morris 1f. Jeffry L. Phillips 1g. Marc Racicot 1h. Heidi B. Stanley 1i. R. John Taylor 1j. Dennis P. Vermillion 1k. Janet D. Widmann - P33771 D03435

D03436-P33771