This is too broad a topic to be answered via a simple question my view:
You could use Workflow Foundation (part of the .net framework) can write a Web front end running against that. I had to do something similar pre WF/WWF (a Mortgage Processing app) and we had to implement a finite state machine (though you might need a petrinet) and rules engine. Workflow systems tend to be quite heavy, especially financial ones.
I would google /research:
- .net Workflow Foundation
- Microsoft Business Rules Engine (though WF has one built in)
- Biztalk (if developing for a large insurance company with complex requirements)
Biztalk costs money. If you are doing this as a student project even WF might be overkill, but it is useful if:
1) The process is complicated
2) Most of time in of the process is spent "waiting" between steps (e.g. for letters)
3) The process can change
4) New insurance rules are needed