A longtime partner of Indianapolis-based Greenwalt Sponsel & Co. Inc. has left the accounting firm and started his own after he said it became apparent he would not become managing partner.

Tom Sponsel, 56, launched Sponsel CPA Group earlier this month and is leasing 10,000 square feet of office space at the Gateway Plaza building at 950 N. Meridian St.

Sponsel said he’s invested $2 million to start the new firm and plans to hire a total of 30 employees by the end of 2010. He so far has taken 15 employees with him, including three other partners.

A disagreement over the direction of Greenwalt Sponsel’s succession plan led Sponsel to leave, he said.

“That was the original plan; I was supposed to be the next managing partner,” Sponsel said.

Current Greenwalt Sponsel Managing Partner Larry Greenwalt acknowledged Sponsel had been expected to succeed him as the firm’s leader in January 2011. But he said Sponsel failed to deliver on certain commitments and even contemplated leaving the firm.

“He started telling me that he was not happy doing what he was doing,” Greenwalt said. “He was going to give himself to 2008 to decide if he was going to stay with the firm.”

The two have worked together for nearly 30 years. Sponsel and Greenwalt both started at the former Keller Gaughan & Greenwalt accounting firm in 1980. They changed the name in 1987.

Prior to Sponsel’s departure, Greenwalt Sponsel had 31 certified public accountants and 59 full-time employees, ranking it as the 11th-largest accounting firm in the city, according to the most recent IBJ statistics.

Partners joining Sponsel at his new firm are Nick Hopkins, Lisa Purichia and Jason Thompson.

Sponsel said he has taken several clients with him, although he declined to say how many, because some have not divulged they are leaving Greenwalt Sponsel.

Greenwalt insisted the departures have not hurt his firm and said eight partners remain. 

“It’s unfortunate when these things happen,” he said, “but there hasn’t been a major impact on our firm as a result from that.”