Maritime Administration Authorization and Improvement Act This bill revises provisions related to the Maritime Administration (MARAD) and the National Oceanic and Atmospheric Administration Commissioned Officer Corps. The bill addresses several aspects of MARAD, including reauthorizing MARAD programs, including programs associated with maintaining the U.S. Merchant Marine; establishing a tanker security fleet of active, commercially viable, militarily useful, privately owned product tank vessels to meet national defense and other security requirements and maintain a United States presence in international commercial shipping; authorizing a grant program to award maritime career training grants to community and technical colleges for the purpose of developing, offering, or improving educational or career training programs for American workers related to the maritime workforce; assessing foreign subsidies to international shipping; and establishing a standing committee of experts to explore and advise on supply chain transportation system vulnerabilities and disruptions and how to minimize them in the event of emergencies and disasters such as the COVID-19 (i.e., coronavirus disease 2019) pandemic. Additionally, among other provisions, the bill sets forth new requirements for the corps concerning commissioned grades and operational strength numbers, obligated service requirements, training and physical fitness, education loan assistance, recruitment, hiring and promotions, separation and retirement, and other workforce issues.