This legislation, known as the International Maritime Pollution Accountability Act of 2025, aims to address the significant environmental impact of the marine shipping industry. Congress finds that marine shipping contributes nearly three percent of global anthropogenic carbon dioxide emissions, which are rapidly increasing. Furthermore, port operations are a major source of air pollution, leading to adverse health outcomes in surrounding neighborhoods.

Beginning January 1, 2027, operators of "covered voyages"—self-propelled vessels of 5,000 gross tonnage or more transporting cargo or freight—will be required to submit comprehensive quarterly reports to the Environmental Protection Agency. These reports must detail information such as port of origin and destination, total distance and time traveled, mass of fuel consumed (including in U.S. waters and polar regions), and cargo mass.

The bill mandates the assessment of a fee on lifecycle carbon dioxide-equivalent (CO2-e) emissions from these vessels. This fee, initially set at $150 per metric ton of CO2-e, will be adjusted annually for inflation plus five percentage points and tripled for fuel consumed in polar regions. It also includes provisions for crediting amounts paid under global economic measures and imposes penalties for late payments. An alternate fee mechanism applies to importers whose cargo is offloaded at foreign ports but ultimately bound for the United States, prorated based on the cargo's share.

In addition to CO2-e, the bill imposes fees on criteria air pollutants, specifically nitrogen oxides, sulfur dioxide, and fine particulate matter (PM2.5), emitted within the U.S. exclusive economic zone, territorial sea, and internal waters. These fees are calculated based on the mass of fuel consumed and specific rates per pound for each pollutant, also subject to annual inflation adjustments and penalties for non-payment.

A significant portion of the collected fees, starting in fiscal year 2029, will be appropriated to various programs designed to decarbonize shipping and ports. Twenty-five percent of the funds will go to the Maritime Administration to provide grants, rebates, and low-interest loans for modernizing the Jones Act fleet, replacing or retrofitting vessels with zero-emission technologies like batteries or low-carbon fuels. Another twenty-five percent will fund competitive grants through the Department of Energy for research and development of low-carbon maritime fuels and low-emission technologies.

Further allocations include five percent for workforce development and training related to zero-emission port equipment and vessels, administered by the EPA. Ten percent each is designated for the electrification of harbor craft (excluding ferries) and ferry vessels, providing grants and loans for battery-electric propulsion and associated workforce training. These programs prioritize projects that maximize reductions in greenhouse gas emissions and criteria air pollutants, improve public health, and alleviate pollution in disadvantaged communities.

Finally, five percent of the collected fees will support increased air monitoring in port communities, funding fenceline monitoring at port boundaries and in nearby neighborhoods. The remaining funds are allocated to existing environmental initiatives: fifteen percent for the EPA's Clean Ports Program, three percent for the National Oceans and Coastal Security Fund, and two percent for the Marine Debris Foundation.