What sets John Rettig’s CFO journey apart from most is not just its length—spanning more than two decades—but its unusual symmetry. His CFO career roughly divides into two decade-long tenures: first helping scale a digital advertising firm from $15 million to $250 million in revenue, and now serving as CFO of Bill, where he’s helped lead the company from startup to public market success.

When Rettig joined Bill, the company had just $13 million in revenue and a modest employee base. What drew him in, he tells us, was the combination of people, culture, and a product that placed finance operations at the center of its design. It was the first time in his career that he’d worked this closely with a finance-focused technology platform.

At the time, Rettig anticipated a 10x growth opportunity—similar to his earlier experience. “It turns out, it’s 100x,” he tells us. Today, Bill has 2,500 employees, serves 500,000 customers, and supports a network of 7 million members. The company processes $300 billion in annual payment volume and has grown to $1.5 billion in revenue.

Much of that growth, Rettig explains, has come from addressing the operational challenges of small and midsize businesses. Early efforts to modernize paper-based processes helped shape the company’s current offerings, which span accounts payable, receivable, corporate cards, and cash flow management.

“We become the center of their financial operations,” Rettig says of the platform’s role. His focus remains on scaling Bill’s impact across the “Fortune 5 million.”