Systemic Risk Designation Improvement Act of 2017 (Sec. 2) This bill amends the Dodd-Frank Wall Street Reform and Consumer Protection Act to allow the Federal Reserve Board (FRB) to subject a bank holding company to enhanced supervision if: (1) the company has been identified as a global systemically important company; or (2) the risk of the company's financial distress, or the nature of the company's activities, could pose a threat to the financial stability of the United States. Currently, companies are subject to this type of oversight if they possess at least $50 billion in assets or are a nonbank financial company under the FRB's supervision. The Financial Stability Oversight Council must approve of any metrics used by the FRB in determining by regulation that a category of bank holding companies is subject to enhanced supervision. Under this bill, companies subject to enhanced supervision may be required to limit mergers and acquisitions, restrict products offered, or maintain a certain debt ratio. (Sec. 3) The FRB must publish the list of companies that have been identified as requiring enhanced supervision. (Sec. 5) The bill provides for the temporary extension of fees and assessments collected from specified bank holding companies under current law, and includes a limit on the total amount collected under the extension.