Reduce Financial Barriers to Immigration and Citizenship Act of 2021 This bill prohibits the Department of Homeland Security (DHS) from charging fees for certain immigration applications (or petitions), requires DHS to provide fee waivers to certain applicants, and addresses related issues. DHS may not impose fees for certain applications for or related to (1) asylum or refugee status, (2) special immigrant juvenile status, (3) U or T non-immigrant visas (victims of certain crimes such as human trafficking), (4) the Violence Against Women Act, (5) special immigrant status for Afghan or Iraqi nationals employed by the U.S. government, or (6) immigration-related fee waivers. DHS must also waive immigration-related application fees for an applicant who receives a means-tested benefit or meets certain conditions related to financial hardship. However, DHS is not required to provide fee waivers for applications for certain employment-based immigration benefits. Receipt of a fee waiver may not be used as a factor (1) for determining whether an alien should be considered a public charge, or (2) when considering an affidavit of support filed by a sponsor. The bill also requires all collected immigration-related adjudication fees to be used only to fund the adjudication and administration of immigration benefits and naturalization.