Based on stereotype of fears, you could add horns to the costume. No offense, Auditor!

I haven't had bad experience with IRS... in fact a few years ago I was told I owed money, and asked for an extension... and they sent me an apology because it was their error. I thought that was pretty dang cool.

These horn barettes are handy and available online.. easier to use than the kind you attach, if you don't need super-realism.

Like these. http://i247.photobucket.com/albums/g...girl/horns.jpg