The Northern Indiana Public Service Company has announced a one-time credit totaling $4.1 million to its natural-gas customers.

“The credit is the result of a decision made by the Indiana Utility Regulatory Commission on how costs associated with unaccounted-for-gas are measured and applied to customer bills,” NIPSCO said in a statement released on Thursday. “NIPSCO is seeking further clarification from the Commission regarding how and when the credit will appear.”

“Unaccounted-for-gas, which is common among natural gas utilities across the country, represents the amount of natural gas that escapes a utility’s pipeline system before it gets used by customers,” NIPSCO said.

In Indiana, cost recovery for unaccounted-for-gas is part of the rate-making process and it must be reviewed by the IURC before being recovered by customers, NIPSCO said.

“NIPSCO has an effective gas pipeline replacement program to ensure the safe and reliable delivery of natural gas to its customers,” NIPSCO said. “While NIPSCO has among the lowest unaccounted-for-gas rates in Indiana, the company continually works to deliver maximum efficiency.”

“NIPSCO’s natural gas bills to its customers are the lowest in the state,” NIPSCO said.