UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): August 9, 2012

AVISTA CORPORATION

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: 509-489-0500

Web site: http://www.avistacorp.com

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Section 8 – Other Events

Item 8.01 Other Events.

On August 9, 2012, Avista Corporation (Avista Corp.) entered into separate Sales Agency Agreements (each, an “Agreement” and collectively, the “Agreements”) with BNY Mellon Capital Markets, LLC (BNYMCM) and UBS Securities LLC. Under the terms of the Agreements, Avista Corp. may offer and sell up to 2,726,390 shares of its common stock, no par value, from time to time through either BNYMCM or UBS Securities LLC, as Avista Corp.’s agents for the offer and sale of the shares. Unless earlier terminated, each Agreement will terminate upon the earlier of (i) the sale of all of the Shares through such Agreement or (ii) December 1, 2015.

Concurrently, Avista Corp. terminated the Amended and Restated Sales Agency Agreement with BNY Mellon Capital Markets, LLC dated December 16, 2009 and further amended on August 25, 2010.

The offering of shares will be made pursuant to Avista Corp.’s registration statement previously filed with the Securities and Exchange Commission (SEC) (File No. 333-163609), which became effective on December 9, 2009 (the “Registration Statement”). Avista Corp. filed a prospectus supplement with the SEC in connection with this offer and sale of shares.

This Current Report on Form 8-K is being filed for the purpose of filing an exhibit to the Registration Statement. Such exhibit is hereby incorporated by reference into the Registration Statement.

This Current Report on Form 8-K does not constitute an offer to sell or a solicitation of an offer to buy the securities described herein, and there shall not be any sale of these securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The sale of securities is being made only by means of a prospectus and related prospectus supplement.

Section 9 – Financial Statements and Exhibits

Item 9.01 Financial Statements and Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.