I think he's talking about What do you do with the physical document (i.e., the Visa bill itself that you have to call about).
I keep wrestling with this, but end up doing like CSGiles, and put it in a special designated area of my desk (assuming it doesn't go with something that already has official files). However, this seems to be counter productive because then every time my eyes fall on it, it screams "Why aren't you doing me?" like the garage that needs to be cleaned in DA's FAST tapes.
So I started a pile of file folders for stuff like this. Temporary files, if you will. Pretty colors so they don't get mixed up with regular manila files. I just stick a post-it note on the label area of the tab and throw the visa bill in and stick them on the shelf. Voila, clean desk. BUT, if the appointment on your calender or NA on your todo list doesn't remind you to do it, the visa bill is out of sight-out of mind, lost and gone until much too late. Theoretically, one would go through these folders at the weekly review to make sure nothing stagnates in there, but I'm still working on that.