Prove It Act of 2017 This bill authorizes the Small Business Administration (SBA) to request the Office of Information and Regulatory Affairs of the Office of Management and Budget to review any federal agency certification that a proposed rule, if promulgated, will not have a significant economic impact on a substantial number of small entities and so need not submit a regulatory flexibility analysis of the rule. If it is determined, after a specified procedure, that the proposed rule will, if promulgated, have a significant economic impact on a substantial number of small entities, the federal agency shall then perform both an initial and a final regulatory flexibility analysis for the rule. An initial regulatory flexibility analysis is prepared in order to ensure that the agency has considered all reasonable regulatory alternatives that would minimize the rule's economic burdens or increase its benefits for the affected small entities, while achieving the objectives of the rule or statute. The request must explain why the SBA disagreed with the certification and statement providing the factual basis for it.