Miller left Gehry Partners LLP to attend Columbia Business School in New York to study entrepreneurship and management. He was on the Dean's List during his studies and worked as a teaching assistant for the university's Greenhouse Entrepreneurship Program and Launching New Ventures Program. During this time, he had the idea to start a healthcare firm based on assisting employees in understanding and making the most of flexible spending accounts (FSA). An FSA, which is set up with an employer, allows employees to spend their income tax-free on medical expenses; however, as Miller discovered while working at Gehry Partners LLC, many employees didn't understand how the process worked and was foregoing the opportunity to cover healthcare-related expenses without paying taxes on the income used for this purpose.