Improving Transparency to Lower Drug Costs Act of 2021 This bill requires the Centers for Medicare & Medicaid Services (CMS) to publish certain payment information regarding pharmacy benefit managers (PBMs) and prescription drugs. Specifically, the CMS must publish certain information, as reported by PBMs, relating to generic dispensing rates, drug discounts and rebates, and payments between PBMs, health plans, and pharmacies, in accordance with specified confidentiality requirements.