How do we set travel OR per diem policies, especially for travel to Regional events and WSBC?

Some intergroup/service boards follow the Internal Revenue Service guidelines for charitable mileage reimbursement. The expense policies are established through group conscience at an intergroup meeting. Looking at past expenses for travel may help the intergroup/service board set some boundaries, and the intergroup/service board treasurer may be able to share what other intergroup/service boards have done with their travel policies.