NAB's new boss Andrew Thorburn, who will take over as chief executive officer from August, is already well versed in the NextGen technology transformation program underway at NAB as its New Zealand arm, BNZ, has been running its own transformation in parallel.BNZ began its five year NextGen technology transformation in early 2013. This closely mirrors what parent NAB has been doing, albeit on a smaller scale - BNZ's entire program is slated to cost NZ$400 million where NAB spent A$200 million on NextGen software alone last financial year.At the heart of both banks' efforts is the replacement of decades-old legacy core banking systems with a modern software platform developed by Oracle in association with NAB. First deployed at NAB's online-only bank UBank, the NextGen platform will allow NAB and BNZ to be nimbler in terms of product development and new customer service offerings.While the Commonwealth Bank is the only one of the four majors yet to have completed a core banking refresh, NAB is now hard on its heels.Last October, NAB's CEO Cameron Clyne said the bank was ahead of expectations on both the NextGen core banking revamp and the ten-year technology transformation, which will see the group replace 10,000 pieces of equipment, transition to a new data centre and have a brand new payments system by 2016 when the program of work is scheduled to be complete.Once complete, the platform is expected to last a decade.While NAB has steered the group-wide technology program, BNZ is no stranger to innovation itself, having pioneered the use of smartphones as payment terminals in New Zealand.Although Thorburn seems unlikely to make many material changes to the strategic direction of the bank's technology investment, he may wish to slow a revolving door which has seen the bank switch chief information officers three times in less than 18 months.In November 2012, then CIO Adam Bennett took on a new overarching technology role in the bank, to be replaced in April by Denis McGee. McGee has since been replaced by former EY partner (and former Commonwealth Bank technologist) David Boyle, who took on the NAB CIO role earlier this year.