Closing the Meal Gap Act of 2020 This bill revises the requirements for calculating Supplemental Nutrition Assistance Program (SNAP, formerly known as the food stamp program) benefits. The bill increases the minimum SNAP benefit and requires benefits to be calculated using the value of a low-cost food plan. The Department of Agriculture (USDA) must determine the requirements for the low-cost food plan, which is the diet required to feed a family of four, consisting of a man and a woman 19-50 years of age, a child 6-8 years of age, and a child 9-11 years of age. USDA must make adjustments to the plan to account for household size, changes in the cost of the diet, and the costs of food in specified areas, including U.S. territories such as Puerto Rico and American Samoa. The bill modifies the requirements for calculating household income to determine SNAP eligibility by (1) authorizing a standard medical expense deduction for households containing an elderly or disabled member, and (2) eliminating the cap on the deduction for excess shelter expenses. The bill eliminates certain work requirements for SNAP. The requirements apply to able-bodied adults who are ages 18-49 and have no dependent children. Under current law, the requirements are partially suspended due to COVID-19 (i.e., coronavirus disease 2019). The bill allows Puerto Rico, American Samoa, and the Northern Mariana Islands to participate in SNAP after submitting a plan of operation that is approved by USDA. Under current law, the three territories receive block grants instead of participating in SNAP.