Methane Border Adjustment Mechanism Act

This bill creates a tax on imported oil and gas (defined as "methane adjustment substances") based on the methane emissions associated with their production in the exporting country. Importers pay the tax, which is calculated by comparing the volume of imported product to the total production in that country, multiplied by the emissions charge a foreign producer would pay under U.S. Clean Air Act rules. It aims to reduce global methane emissions by making high-emission imports more expensive, while encouraging international cooperation with major oil/gas importers to adopt similar measures. The tax applies to sales/use after December 31, 2024, and includes provisions for tracking supply chain emissions and expanding the mechanism to other oil/gas-dependent products.