Protecting Americans with Pre-Existing Conditions Act of 2021 This bill nullifies specified guidance and final rule provisions pertaining to Section 1332 waivers (also known as State Innovation Waivers or State Relief and Empowerment Waivers) issued by the Department of the Treasury and the Department of Health and Human Services. The provisions allow states to forego certain requirements of the Patient Protection and Affordable Care Act in order to implement experimental plans for health care coverage, as long as the resulting coverage meets certain statutory criteria. The provisions, which supersede earlier guidance from 2015, alter agency interpretation of how states may satisfy the statutory criteria for waiver approval. For example, the provisions (1) redefine acceptable coverage under such waivers to include short-term, limited-duration insurance and association health plans; (2) allow the comprehensiveness and affordability of coverage under such waivers to be assessed based on projected availability, rather than enrollment; and (3) allow the level of coverage to be assessed based on the effects over the entire course of the waiver, rather than per year.