Giving Retailers and Our Convenience Employees Relief Act of 2020 or the GROCER Act of 2020 This bill excludes from gross income, for income tax purposes, compensation and other income up to $25,0000 paid to certain retail grocery and gasoline service station employees between the period of February 15, 2020, and June 15, 2020, who are working in a county that has at least one confirmed case of COVID-19 (i.e., coronavirus disease 2019). The period may be extended for an additional three months if the Department of the Treasury determines that the COVID-19 emergency is likely to be ongoing during such extended period.