Papers in waiting
This may sound silly to some GTD'ers, but I treat that type of situation like a Project. It sounds like it is one anyway--will filling out those forms be the end of it, or do they need to be delivered or mailed? If that one task will not be your final outcome, this is a Project. Therefore, those forms would go in a Project Support folder that is labeled (all of which should take less than 60 seconds).
I had struggled with including such outcomes on my Projects list, but my system's quality has improved by doing so.
In the same way David Allen will make a Reference folder for a single business card, I will write a single load of laundry on my Projects List if I am not there to do it start to finish (folded clothes put away).
I think the colored folders idea, above, would work well for someone who consistently did it, but I have opted not to. I prefer to have one place to look for support documents.
Hope this helps
JohnV474