Acting to Cancel Copays and Ensure Substantial Savings for Biosimilars Act of 2020 or the ACCESS for Biosimilars Act of 2020 This bill temporarily eliminates cost-sharing for biosimilar biological products for certain qualifying beneficiaries under Medicare medical services. Specifically, the bill eliminates cost-sharing for beneficiaries whose coverage under private health insurance, a federal program (other than Medicare), a Medicare supplemental policy, or Medicare Advantage does not already do so. The Centers for Medicare & Medicaid Services must establish a process for determining a beneficiary's eligibility and notifying Medicare Advantage organizations of such determinations. The bill's provisions apply to products that are furnished during the five-year period beginning on January 1, 2021, or the date on which the product is first marketed, whichever is later.