I think this depends on if you are talking about figuring out what contract a company had some time ago (say 18 months), or if you talk about the current defaul

I think this depends on if you are talking about figuring out what contract a company had some time ago (say 18 months), or if you talk about the current default value. The last one should be very easy to find in the code and if you are migrating to a new system the information should be transferred in some way. For historical things you obviously has to store the data somewhere and then just figure out a nice way to do that. In this case it could just be a table of default contracts with some fields and a startdate. Then you can query for any point in the past and get the default contract that was active at that point.