The latest acid test for the Commonwealth Bank's core systems revamp arrives at the end of the month when the bank turns off its legacy deposit system and switches over to the new deposit modules developed in association with industry partners SAP and Accenture.The CBA is now mid-way through its $730 million modernisation and transformation program, with just the lending and transactions systems to complete over the next year and a half. Already this has led to the group shifting gears, with the investment priorities in information moving away from being a source of savings (having delivered $300 million of savings over the last three years) and becoming an engine for growth for the bank.According to group executive and chief information officer, Michael Harte, the bank's IT group has been undergoing a transformation since he joined in 2006. Part of that has involved developing the know-how about "how to develop new services, how to launch those new services, and deal with the legacy" which has been gleaned through the core systems project. Creating a culture of excellence and genuine customer focus in the 2300 strong IT group has been a priority for Harte, who says that: "We have created a critical mass of how products are developed, supported, brought into production, and the old legacy systems converted and migrated and shut down."The initial core revamp program announced in May 2008 was costed at $560 million; however the program grew to $730 million in order to integrate core systems overhauls for subsidiaries ASB and BankWest. If the business case stacks up, these subsidiaries are expected to take another three years to complete the migration to the new core.Although the scope of the project was extended, Harte's team has kept a tight rein on costs and time - a rare achievement in IT projects of such scale.According to Harte: "The secret sauce is business pull rather than IT push - Ralph's (CBA CEO Ralph Norris) governance, close board scrutiny and executive sponsorship within the businesses." Close alliance with the business groups and an understanding of the role they play in the bank is critical to the success of the transformation process, according to Harte."Perhaps greatest of all is having a leadership team that has developed the game plan and is executing with urgency." Harte also lauds the IT professionals, whom he describes as highly engaged and "committed to focused execution and delivering a superior customer experience."Working closely with the business led to the understanding that changing the core banking systems in isolation was not enough - and that the administration systems required overhauling in tandem. As a result CBA has been running a general ledger and risk upgrade using Oracle's PeopleSoft.Core banking systems revamps are a far from trivial undertaking, but Harte has his sights set even higher. He wants to digitise as much of the banking process as is possible, in order to deliver new levels of agility to the institution."The most informative analogy is Tesco. The big supermarket chain used