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

November 5, 2013

(205) 326-2700

(Registrant’s telephone number including area code)

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:

Alabama Gas Corporation (Alagasco) is subject to regulation by the Alabama Public Service Commission (APSC) which established the Rate Stabilization and Equalization (RSE) rate-setting process in 1983. The Company’s current RSE order had an original term extending through December 31, 2014. At its meeting on November 5, 2013, the APSC voted unanimously to make certain RSE modifications effective January 1, 2014, including the following:

The term will be extended through September 30, 2018.

Alagasco will be allowed an authorized return on equity range of 10.50% to 10.95% with an adjusting point of 10.80%.

Alagasco is eligible to receive a performance based adjustment of 5 basis points to the return on equity adjusting point, based on meeting certain customer satisfaction criteria.

The equity cap upon which a return will be permitted will be adjusted upward to 56.5% with Alagasco allowed to budget at the cap.

The Cost Control Mechanism will be adjusted to allow annual increases to operations and maintenance costs using the June Consumer Price Index-Urban (CPI-U) each rate year plus or minus 1.75% and as adjusted from a 2007 base year, adjusted for inflation using the CPI-U.

Alagasco expects these modifications to be included in a final written order in the fourth quarter of 2013.

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.

2