How do I handle tricky expense reports and policy exceptions?

The routine expenses you have handled. Edge cases feel harder because the rules run out and you are left deciding. That uncertainty is not a gap in your ability; it is the point where judgment takes over from procedure. When policy does not cover it, do not guess in silence. Find the principle behind the rule, ask the person who owns the policy, and write down the answer so the next odd case has a precedent. Complex reports get simpler when you break them into pieces and check each against one clear standard. One small step: start a short notes file of the tricky cases you have solved and how. You are building the rulebook that did not exist, one case at a time.