Thoma, who died in 2004, was a partner in the E.B. Thoma & Son Insurance Agency in Tullahoma, Tenn. In 1946, after returning home from service in World War II, he became a partner with his father in the family business, which was established 1910. The younger Thoma expanded the agency to include real estate and loans in the early 1960s.

When Thoma retired from insurance work in 1983, he was a lieutenant colonel in the U.S. Army Reserves and served in the Reserves until 1999. During his insurance career, Thoma was a member of several professional insurance organizations, including the Independent Insurance Agents of Tennessee, Independent Insurance Agents of America, the Professional Insurance Agents and the Southern Agents Conference.

Thoma also had a long affiliation with Insurors of Tennessee, serving on its board of directors and becoming its president in 1983. In 1987, he was recognized as state Insuror of the Year.