Supporting Charitable Institutions Act of 2020 This bill allow a new tax credit for charitable contributions made in cash during 2020 to a charitable organization for relief efforts connected to COVID-19 (i.e., the coronavirus disease 2019). The credit is limited to 24% of contributions not exceeding $4,000 for an individual taxpayer, $6,000 for a head of household, and $8,000 for a married couple filing a joint return.