Flood Resiliency and Taxpayer Savings Act of 2021 This bill requires federal agencies to take specified actions to evaluate and mitigate the risk of floods to federally funded projects. Specifically, the bill directs federal agencies to evaluate the potential for flooding throughout the planned lifetime or duration of a federally funded project to reduce the risk of financial and property losses and prevent the disruption of critical services during floods. Further, federal agencies must consider certain data and information (e.g., the most recent flood insurance rate map published by the Federal Emergency Management Agency) when evaluating whether a federally funded project is in a floodplain. If the agency determines the data and information are not adequate for understanding the flood risks to the project, then the agency must use an alternative design standard outlined by the bill. Finally, the bill directs the Federal Interagency Floodplain Management Task Force to issue guidelines for federal agencies related to flood risk management.