The sign outside the Central Maine Power Belfast Service Center is pictured on April 14.

AUGUSTA — Central Maine Power shareholders, not ratepayers, are going to foot the $580,000 cost of an independent audit that found problems with the way the utility handled customer service issues with its new billing system.

The Maine Public Utilities Commission voted Thursday to hold shareholders accountable for the full cost of the audit by Liberty Consulting Group of Pennsylvania.

Under Maine law, ratepayers typically pay the full cost of a management audit. But there’s an exception if an investor-owned public utility like CMP results in a commission finding of “imprudence.”

Company spokesperson Catharine Hartnett said the utility has no plan to appeal the decision.

Commissioners in January imposed what amounts to a penalty of nearly $10 million on CMP for billing problems and poor customer service.

The PUC staff concluded that defects associated with CMP’s SmartCare billing system, along with human errors, caused delayed bills or errors for “tens of thousands of customers.”