Good morning. There’s a continuing trend of finance chiefs becoming chief operating officers (COOs), taking on dual COO roles, or even combining the CFO and COO positions. This shift is largely driven by the ever-expanding remit of the finance chief and the increasing needs of companies.Over a 25-year career in strategic finance leadership, John Rettig has witnessed the CFO role transform in profound ways. Now serving as president and COO of the finance software company Bill, Rettig’s journey reflects the sweeping changes that have redefined what it means to be a finance leader.Rettig, who joined Bill as CFO in 2014, began his COO role earlier this month to further accelerate company growth. He was succeeded as CFO by Rohini Jain, who joined Bill from PayPal, where she most recently served as CFO and SVP of Large Enterprise and Merchant Platforms.I sat down with Rettig to get his perspective on his move from finance chief to COO.“The impact and influence of the CFO have broadened dramatically compared to 25 years ago,” Rettig explained. Over the last decade, what he describes as the era of “CFO 2.0,” the job has shifted from simply reporting numbers to acting as a strategic advisor and true business partner to the CEO. “I’ve lived this transition myself, and my peers across tech and growth companies have seen the same thing,” he said. With the prevalence of AI, he believes we are now entering a new era—“CFO 3.0.” Finance chiefs must have a comprehensive understanding of technology deployed by the company, he said.Rettig emphasized that the discipline and understanding required to communicate precisely—especially in the high-stakes context of a public company—are valuable assets when transitioning to a COO role.“You really need to have visibility on execution, understand results, know where to dig deep, and gain a bottom-up understanding of how things work,” he said. This process can lead naturally to operational leadership responsibilities, including partnering with leaders across the business in the age of AI, he noted.No ‘status quo’AI is moving at “exponential speed,” even compared to just a year ago, Rettig said. “I think the exciting part about that is there’s no longer a status quo. AI is coming for everything.” This brings both tremendous opportunities and disruptive threats, he added.For Rettig, success now requires an attitude of constant reinvention—leaning into emerging technology, experimenting boldly, and never being afraid to overhaul your business model before someone else does. “This is really powerful for the role of the CFO or COO, and the entire executive team,” he said.Regarding Bill’s AI strategy, Rettig highlights two key areas: customer-facing products that automate complex financial processes and transformative internal improvements. “It’s not just about making work more efficient,” he explained, “it’s about using technology to eliminate work entirely.”As president and COO, Rettig continues to focus on both short-term execution and long-term vision. During his tenure at Bill, which serves small and mid-sized businesses, the company has grown from 140 to 2,500 employees. His top priorities now include accelerating time-to-market, preparing the organization for future scale through investments in automation and operational efficiency, and making sure every resource is directed to its highest-value use. A big part of his role will also be fostering company culture. “I’ve been with Bill for over 11 years now, which is a really long time in a Silicon Valley tech company,” Rettig said. The most important reason he came to Bill was the people. “And I’m still here for that same reason,” he said.Sheryl Estradasheryl.estrada@fortune.comThis story was originally featured on Fortune.com