More than half of all bills in America are now paid online; though when it comes to who's doing the paying, major generation gaps exist, according to new data from electronic payments company ACI Worldwide and research firm Aite Group.

The study of 2,429 U.S. consumers during the third quarter of 2016 found that 56% of all bills are paid online today and that most consumers paying online do so via billers' websites rather than via financial institution bill pay or third-party bill pay sites. Millennials and Gen Xers pay the largest proportion of their bills online (61% and 60%, respectively), the study added.

"While a large segment of older Americans still pay bills through the mail, in-person and by check, overall trends are shifting toward online and mobile bill payment," Aite Group Senior Analyst David Albertazzi said. "Banks and billers need to have a long-term view and dedicate resources to digital channels that provide a frictionless payment process and encourage consumers to pay online and through automated channels."