The Transit Funding Flexibility Act broadens the permissible uses of urbanized area formula grant funds under title 49, United States Code. It removes the existing population-based restriction, allowing any recipient of these funds to utilize them for the operating costs of public transportation equipment and facilities, rather than only those in areas with populations under 200,000. To ensure responsible use, the bill introduces a new requirement for recipients to submit an annual certification of maintained effort , attesting they will uphold their financial commitment to operating costs for which grant funds are used. If a recipient fails to maintain effort as certified, the Secretary is mandated to reduce their grant amount for the subsequent fiscal year by one-third.