Question: Every college seems to grant application fee waivers, but none of them define who is eligible for a fee waiver. What is the income bracket under which waivers are granted? Also, are there any other criteria?
You will find fee waiver eligibility guidelines here: http://www.nacacnet.org/studentinfo/feewaiver/Documents/ApplicationFeeWaiver.pdf
Note, however, that they are indeed just "guidelines" and not hard-and-fast rules. If you don't meet the criteria listed but feel that you may have a special reason to get your fees waived (e.g., recent death or serious illness of wage-earner parent), then speak to your college counselor or write directly to admission officials at your target colleges.