Mike Baird, NAB's chief customer officer of consumer banking, will leave the bank on 15 April.
Baird has been leading NAB's retail banking business since October 2018, with responsibility for more than 700 branches, 7000 bankers, broker partnerships, direct banking, and UBank.
Landing this role, and his friendship with previous CEO Andrew Thorburn, had sparked speculation Baird was being fast tracked as a contender for the chief executive role in a few years. At least he would have been well qualified.
Baird started his work career as a NAB graduate in 1989, later holding senior roles in NAB's corporate and institutional banking team in Australia and London, including head of debt capital markets originations in London.
He was a senior corporate finance manager at Deutsche Bank and head of corporate and institutional banking at HSBC in Australia and New Zealand prior to entering NSW state politics in 2007.
It was therefore a 'back to the future' moment when Baird joined National Australia Bank in 2017, leading NAB's corporate and institutional bank, around six weeks after quitting as NSW state premier.
Then NAB's group CEO and long-time personal contact Andrew Thorburn was forced to resign over cascading scandals at the banking royal commission, the bank chose an "outsider", Ross McEwan, the former head of retail banking at Commonwealth bank and former CEO of part-nationalised UK bank RBS.
NAB Group CEO Ross McEwan said he supported Baird's decision to step down from his executive role and take a break before considering new opportunities.
"I am pleased that he has been part of my leadership team but understand and accept the reasons for his decision to leave," McEwan said in a statement released to the ASX.
"I have an open mind about what I will do next and will use the time to determine where I believe I can make the best, most fulfilling contribution to business and the wider community."
Anthony Waldron, an executive general manager in Baird team, with more than 20 years' experience at NAB and its subsidiaries, will act as chief customer officer, consumer banking, subject to regulatory approvals, while NAB searches for a permanent replacement.
Speculation in The Australian centres on Les Matheson, the RBA retail head as the likely permanent pick. Matheson has lengthy tenure at senior levels of Citi and Westpac in the local market to shape his thinking if he takes the job.