Montana’s largest electric and gas utility wants to charge customers more. NorthWestern Energy says the cost of generating power is rising, and that means bills must go up, too. The decision rests with state regulators, who for the second time this month have found major loopholes in the company’s request.

NorthWestern Energy is asking to raise its energy bill rates by at least 8%. Earlier this month, the Public Service Commission told the utility it needed more information before it could consider that request.

NorthWestern has done that, but regulators say it’s still not enough.

PSC analyst Haylee Gobert told commissioners Tuesday that it is unusual for the utility that NorthWestern has not explained the reasons for a rate increase.

“In other previous filings, there were minor deficiencies and those are usually updated in discovery, whereas this met a higher threshold of deficiency. And so this is the first time we’re seeing this,” Gobert said.

The PSC gave NorthWestern a week to provide more information.

Last fall, the PSC approved NorthWestern’s request to increase rates for customers by 28%.