Subsidy Reserve Act of 2017 This bill amends the Dodd-Frank Wall Street Reform and Consumer Protection Act to require each nonbank financial company supervised by the Federal Reserve Board (FRB) and each bank holding company with total consolidated assets of at least $500 billion to establish and maintain a capital account called a "subsidy reserve." The amount in a company's subsidy reserve shall be based, according to a formula established by the FRB, on the financial benefit received by the company as a result of the expectation of shareholders, creditors, and counterparties that the federal government will shield them from losses in the event of the company's failure. The amount in a company's subsidy reserve may be taken into account for purposes of determining a company's compliance with regulatory capital requirements.