I'm currently a PhD student in mathematics at a well-ranked school. Unfortunately, after a few years of increasing frustration and self-doubt, I'm considering leaving academia and trying to start a different career.
I currently have an NSF graduate fellowship. As described in the information guide for fellows, one's "status" with regards to the fellowship can be either
Tenure: Tenure is the period of time during which Fellows utilize the fellowship to pursue an advanced degree in science, mathematics, or engineering...
Reserve: With prior Foundation approval, Fellows may reserve any two years over the five-year period to use an alternative means of support, or to engage in activities other than graduate study... (emphasis mine)
(There are also options for medical or military deferral. The full description of Tenure and Reserve status are in the linked document.)
Does this mean I can request to reserve my fellowship for the 2015-2016 academic year, using that time "test the waters" on another career, such that if I decide to stay in – or rather, go back to – academia, I would still have my NSF fellowship?
Of course if I do something like this, I would want it to be with my advisor's approval, though I haven't brought up this specific idea with them yet. Let's assume they are okay with it.