</font><font color="blueclass=small">( Andy how much off road diesel does one have to purchase to get IRS to make a house call these days? /forums/images/graemlins/frown.gif )</font>
I have no idea, from what I can tell they just ride around in pairs and stop when ever they feel like it. They knock on your door, walk in with badges in their hands, and hand you a brochure explaining why you need to pay taxes and pentalies for noncompliance. Next they ask if you would like to accompany them as they check your tanks. I don't think quantity has much to do with it.
Even if you are clean, they write up a report and leave you a copy for your files. So far so good here, but I do know a bunch of guys who have gotten caught.
Andy