WALL Act of 2021 This bill appropriates $25 billion for the construction of a wall on the U.S.-Mexico border and addresses other issues related to immigration. As offsets to this spending, the bill restricts the child tax credit, earned income credits, and lifetime learning credits to those with Social Security numbers and not prohibited from employment in the United States. Also, individuals who file taxes using an individual taxpayer identification number (ITIN) instead of a Social Security number must pay a fee ($300 for each individual on the tax return who was issued an ITIN). The bill restricts eligibility for certain federally-funded benefits, including unemployment compensation, supplemental nutrition assistance, and housing benefits, to those eligible to work in the United States. Agencies administering such benefits must use the E-Verify program to confirm the eligibility of applicants for such benefits. This bill also sets fines for aliens who improperly enter the United States or overstay their visas.