International Maritime Pollution Accountability Act of 2023 This bill establishes requirements and incentives to reduce greenhouse gas emissions from the marine shipping industry. Specifically, the Environmental Protection Agency (EPA) must assess fees on certain cargo vessels for emissions of carbon dioxide, nitrogen oxides, sulfur dioxide, and fine particulate matter from fuel consumed during voyages. The fees apply to certain large vessels that are off-loading cargo or freight at U.S. ports. However, the fees do not apply to (1) certain vessels already regulated under the Clean Air Act; or (2) vessels transporting military cargo, food aid, or supplies for disaster or emergency relief. The amount of the fee must be based on the amount of fuel consumed and the quantity of emissions. The EPA must also assess alternative fees on certain cargo vessels that off-load cargo or freight at foreign ports if the cargo or freight is ultimately intended to be transported to the United States. The Coast Guard and U.S. Customs and Border Protection must penalize vessels that do not pay fees by deadlines. The bill also creates incentives related to decreasing greenhouse gas emission from vessels, port equipment, maritime technologies, and harbor crafts. A portion of the revenue generated from the fees must be provided to the EPA, the Maritime Administration, and the Department of Energy to carry out new programs that award such incentives. A portion of such revenue must also be used for certain existing programs related to clean ports, port infrastructure, ocean and coastal security, and marine debris.