Federal Tax Law Investigation

On January 3, 2018, the IURC opened an investigation "into the impacts of the Tax Cuts and Jobs Act of 2017 and possible rate implications." The case is pending as Cause No. 45032.

The OUCC is participating on behalf of Indiana consumers. All rate-regulated, investor-owned utilities are parties to the case. Municipal and not-for-profit utility rates are not at issue.

Rate reductions for customers of the following utilities are expected to take effect in the coming weeks:

  • NIPSCO (electric and gas),
  • Ohio Valley Gas,
  • Seven small natural gas utilities (Boonville, Community, Fountaintown, Indiana Natural Gas Corp., Indiana Utilities Corp., Midwest, and South Eastern Natural Gas), and
  • Certain Aqua Indiana divisions (Aboite Wastewater, Darlington, Lake County Water/Sewer, South Haven, Southern Hills, Wildwood, and Wymberly).

The following utilities have requested, and been granted, subdocket proceedings for further review. Their current rates are expected to stay in effect at least through July 2018:

  • Duke Energy,
  • Indiana American Water Co.,
  • Indianapolis Power & Light Co. (IPL), and
  • Sycamore Gas Co.

The investigation has two phases:

  1. Immediate rate relief
  2. Longer term tax issues


The IURC's February 16, 2018 order required utilities to file revised tariffs by March 26, 2018. The order also gave each utility the option of withdrawing its proposed tariff and seeking further review through a subdocket.

  • Four utilities (listed above) requested subdockets with the IURC approving the requests. Once a subdocket opens, the utility has 10 days to file testimony. The OUCC then has 30 days to respond.
  • If a utility did not request a subdocket, the OUCC was given 30 days to raise any objections to a proposed tariff.
    • If the OUCC did not object, then the utility's new rates are expected to take effect soon.
    • If the OUCC objected, then the proposed tariff is now under further review from OUCC and IURC staff.

Each major Indiana utility is listed below with a link to its proposed tariff and additional information if applicable.


  • Duke Energy has filed and withdrawn its proposed tariff.
    • The IURC has granted the utility's request for a subdocket (Cause No. 45032-S2).
    • The OUCC anticipates filing testimony on June 8, 2018.
  • Indiana Michigan Power (I&M) has been dismissed as a respondent. All issues dealing with federal tax relief are being addressed in the utility’s pending rate case.
  • Indianapolis Power & Light (IPL) has filed and withdrawn its proposed tariff.
    • The IURC has granted the utility's request for a subdocket (Cause No. 45032-S1).
    • The OUCC filed testimony on May 23, 2018, recommending immediate rate relief.
  • Northern Indiana Public Service Co. (NIPSCO): The OUCC did not object to the proposed tariff, and rate reductions were expected to take effect May 1, 2018.
  • Vectren filed a revised proposed tariff on May 11, 2018. It is awaiting Commission approval.
    • The OUCC has reviewed the revised tariff and does not object.




The case's second phase will examine longer term issues including customer credits for rates collected at the 35-percent tax rate since January 1, 2018 and deferred income tax accounting matters.

Each utility's Phase Two issues will be considered in a subdocket, with links to each case file below. The procedural schedule for each subdocket includes the following dates:

  • June 19, 2018: Deadline for utility testimony
  • August 21, 2018: Testimonial deadline for OUCC and any intervening parties
  • September 21, 2018: Utility rebuttal testimony deadline
  • October/November 2018: Evidentiary hearings on dates to be determined

Subdocket case files:

  • Cause No. 45032-S1: IPL
  • Cause No. 45032-S2: Duke Energy
  • Cause No. 45032-S3: Sycamore Gas. Co.
  • Cause No. 45032-S4: Indiana American Water Co.
  • Cause No. 45032-S5: NIPSCO (Electric)
  • Cause No. 45032-S6: Boonville Natural Gas Corp.
  • Cause No. 45032-S7: Community Natural Gas Co.
  • Cause No. 45032-S8: Fountaintown Gas Co.
  • Cause No. 45032-S9: Indiana Natural Gas Corp.
  • Cause No. 45032-S10: Indiana Utilities Corp.
  • Cause No. 45032-S11: Midwest Natural Gas Corp.
  • Cause No. 45032-S12: Ohio Valley Gas
  • Cause No. 45032-S13: South Eastern Indiana Natural Gas Co.
  • Cause No. 45032-S14: Ohio Valley Hub
  • Cause No. 45032-S15: American Suburban Utilities
  • Cause No. 45032-S16: Hamilton Southeastern Utilities
  • Cause No. 45032-S17: LMH Utilities Corp.
  • Cause No. 45032-S18: South Haven Sewer Works
  • Cause No. 45032-S19: Aqua Indiana
  • Cause No. 45032-S20: Community Utilities of Indiana
  • Cause No. 45032-S21: Vectren (Electric and Gas)

All publicly filed documents in both phases of the investigation are available from the IURC's website.

Written consumer comments are invited for the case record. The OUCC's Speaking Out on Pending Cases fact sheet offers more information.

This page will be updated based on case developments.