The study - in which Aspen Analytics analysed transactional data from nearly 10 million customers over 16 months at a major US bank - found that customers who began using online bill payment during the course of the research delivered 15% to 20% more profit to their financial institution when compared to similar customers who did not adopt the service.

Every additional bill that customers paid online resulted in an incremental increase in customer profitability. Consumers who paid an average of five bills or more online per month were four times as valuable to their bank as average customers.

Meanwhile, those using online bill pay services most actively carried 79% higher account balances than the average.

In addition customers who paid bills online were 76% less likely to churn or leave the bank, with the figure rising to 95% for people paying five or more a month.

Fiserv says that decelerating online payment activity from customers also served as an early "red flag" that they were likely to move their account to another institution in the near future, providing the bank with an opportunity to take preventative action.

Kirk Gripenstraw, senior director of analytics, Aspen Analytics, says: "Consumers get hooked on the convenience of these services and don't want to go through the time-consuming transition of accounts and bill payment transactions that would result from moving to another bank or credit union."

Although profitable, the provision of free online bill payment services to retail banking customers is also expensive, and will cost the US financial services industry $1 billion by 2010, according to research published by TowerGroup last August.

The research house estimated that nearly 24 million Americans used electronic bill payment and presentment services (EBPP) with Usage increasing at a compound annual growth rate (CAGR) of 18% and set to rise from 2.11 billion transactions in 2008 to 3.87 billion in 2012.

But TowerGroup warned it is becoming increasingly expensive for credit crunch-hit banks to deliver and support bill payments for customers.

Providing online bill payments to retail customers would cost the industry around $903 million in 2008 as banks looked to outsource the provision of user interfaces, processing and customer service to third parties, predicted the firm.