Policy Memorandum: Fee Waiver Guidelines as Established by the Final Rule of the USCIS Fee Schedule; Revisions to Adjudicator's Field Manual (AFM) Chapter 10.9, AFM Update AD11-26 [open pdf - 78KB]
"This Policy Memorandum (PM) provides guidance on processing fee waiver requests filed pursuant to 8 CFR 103.7(c) as amended by changes made in the final rule 'U.S. Citizenship and Immigration Services [USCIS] Fee Schedule,' published in the Federal Register (FR) on September 24, 2010. See 75 FR 58961."
Policy Memorandum: PM-602-0011.1
U.S. Citizenship and Immigration Services: http://www.uscis.gov/