If you haven't explicitly thought about the second-order consequences, something like "I'm almost certain Jane from accounting knows best how to handle that sor

If you haven't explicitly thought about the second-order consequences, something like "I'm almost certain Jane from accounting knows best how to handle that sort of thing, and if not then she definitely knows who to talk to" would seem plenty polite. It solves the asker's problem as best you're able, and it's proactive and friendly.