An insurer that operates solely in one state and has its main office there is most accurately termed what?

A domestic insurer is one that is incorporated and operates in the state where it has its main office. This means it is licensed to do business within that specific state, and all regulatory oversight falls under the jurisdiction of that state's insurance department.

In contrast, an admitted insurer is one that has received a license to operate in a state but does not necessarily mean it is based there. A foreign insurer operates in one state but is incorporated in another state. An alien insurer is one that is incorporated outside of the United States but conducts business within the country. Therefore, a domestic insurer is the most accurate term for an insurer that operates exclusively within its home state and has its main office located there.