Territorial Equity Act of 2021 This bill alters provisions relating to the treatment of U.S. territories under Medicaid, Medicare, Medicare Advantage, the Supplemental Security Income (SSI) program, and other federal assistance programs. The bill modifies provisions under several health care programs with respect to U.S. territories. Among other changes, the bill eliminates Medicaid funding limitations for U.S. territories beginning in FY2022, repeals provisions that exclude residents of Puerto Rico from a certain automatic enrollment process for Medicare medical services, establishes minimum criteria for certain elements used in Medicare Advantage payment calculations for areas within U.S. territories, and allows residents of U.S. territories who are unable to obtain health insurance through their employer or a health insurance exchange to instead obtain coverage that is at least as broad as the coverage available to Members of Congress and their staff through the District of Columbia exchange. The bill also modifies provisions under other federal assistance programs. Among other changes, the bill allows Puerto Rico, American Samoa, and the Northern Mariana Islands to participate in the Supplemental Nutrition Assistance Program (SNAP, formerly known as the food stamp program); makes residents of Puerto Rico eligible for the federal earned income tax credit; and extends the SSI program to Puerto Rico, Guam, the Virgin Islands, and American Samoa.