The Citizens Action Coalition of Indiana is recommending that the Northern Indiana Public Service Company LLC expand the time frame of refunds for more than 4,000 customers who were billed incorrectly for years due to malfunctioning gas meters.
The public interest group submitted testimony to the Indiana Utility Regulatory Commission on Friday from Program Director Ben Inskeep, which detailed the problem and laid out potential solutions for both customers and the utility.
NIPSCO discovered that its mechanical meter indexes weren’t rotating at the correct drive rate in a part of its legacy gas meters. The issue came up when NIPSCO ”began installing gas AMI communications modules” in 2024, according to the CAC’s Sept. 4 filing.
For example, if someone’s usage was 10 therms of gas, the meter recorded 20 therms, according to Post-Tribune archives.
Through April 30, 4,004 customers were identified as being overbilled, while around 500 customers were underbilled, according to data in the filing. About 285,000 of the 910,000 AMI modules were still awaiting installation as of late April, so the full number of affected customers is incomplete.
Inskeep concluded his testimony with recommendations, including the utility refunding all overcharges back to the earliest date supported by its records, potentially as far back as 2010, as well as any related fees. He also suggested NIPSCO should pay 8% simple interest on all refunds to compensate customers for the time value of money.
In a Friday statement, NIPSCO said it is reviewing testimony in this cause and will file rebuttal testimony on October 1. The IURC will conduct an evidentiary hearing in the case on Oct. 22 in Indianapolis.
NIPSCO first notified the IURC about the issue in September 2025, according to the testimony, but customers and the CAC weren’t aware of the issue until the utility filed its case in March 2026.
At this point, NIPSCO is providing a refund for 12 months of usage pursuant to IURC rules and regulations. For customers who were billed for less than actual usage, NIPSCO is not seeking to recover for any prior usage.
Inskeep’s testimony said some affected customers had reached out to the company about high bills, but usually just received assurances that their meters were accurate when they were actually being billed for twice their usage.
In its March filing, NIPSCO said it doesn’t know when the index issue started and has said it’s possible it occurred either when the meters were first manufactured, when they were first installed, when the AMR modules were installed or at some other time. Some of the affected meters include those installed as early as 1972, with most being installed between the 1970s and 1990s.
“Thus, some customers may have been overcharged for more than 50 years, and thousands more for 20-50 years,” Inskeep wrote. “This could be the longest, or one of the longest, periods in which thousands of natural gas customers were massively overcharged for service by a utility in U.S. history.”