Protecting Taxpayer's Return on Investment Act of 2020 This bill sets forth requirements for the purchase or guarantee of a company's assets by the Department of the Treasury in response to the COVID-19 (i.e., coronavirus disease 2019) pandemic. Specifically, as a condition of such a transaction, companies must provide a warrant (i.e., the right to purchase company stock in the future at a specified exercise price) or a senior debt instrument to Treasury. The exercise price for a warrant must be set by Treasury for the primary benefit of taxpayers. Treasury is generally prohibited from purchasing or guaranteeing assets from an inverted domestic corporation (i.e., a domestic corporation that has been restructured to incorporate in a foreign jurisdiction for tax purposes) in response to COVID-19. An entity receiving specified assistance in response to COVID-19 may not claim the trade or business expenses tax deduction for the amount an individual employee is compensated above $500,000.