Just working through some ideas here, hoping that writing it out will clear it up in my head, or if not, then someone else may give me some feedback.

I'm working on some software for an Insurance Company. We have Insurance Policies based on Plans and Plans have Premium Rates which vary according to smoker, age & sex of the Policy Holder and the sum assured of the Policy. For an individual Policy I need to calculate the premium due. So I'll create a CalcPremium() function on the Policy BO. Within this function I need to get the Premium Rate to use. Should I have a GetPremiumRate() function on the Policy BO which pulls the data from the Premium Rate table, or should that be on the PremiumRate BO?