BOSTON (WBZ NewsRadio) — National Grid customers could have to dig even deeper in their pockets next winter.

In an email to customers, the utility disclosed it's asking for another rate hike of as much as 12%. According to the statement, the hike would generate $144 million for upgrades to the gas delivery system.

But some customers aren't happy about the proposal.

"We can't afford no more. It's enough already," one resident said. Another adding "You look at the bill, and you're like, wow, you know, that's a lot, a lot of money."

Read More: Residents Sound Off About Rising Costs Of Electric Bills During The Winter

The rate hike still needs approval from the Department of Public Utilities. Customers will have a chance to weigh in on the matter over the next month at a series of public hearings and online.