TORONTO -- The Canadian Imperial Bank of Commerce is refunding 1.4 million customers for improperly charging credit card fees over 14 years.

The country's fifth-largest bank says some credit card accounts in Canada may have been incorrectly charged a fee for exceeding the credit limit between 2003 and 2017.

Higher insurance premiums were also charged on optional creditor insurance.

Refunds are being made with interest.

Average refunds of about $50 will be issued until October.

CIBC is notifying affected current and former clients directly.

The bank declined to disclose how the error was discovered but says the issues have been corrected.