Assistance for Firms Harmed by Tariffs on Exports Act This bill expands the authority of the Department of Commerce to provide trade adjustment assistance (i.e., assistance provided to companies that are adversely affected by competing imported goods and services) to firms. Specifically, Commerce may provide such assistance to a firm that has experienced a decrease in the export of the firm's articles or services as a result of tariffs imposed on such exports by a foreign country in response to U.S. tariffs imposed on the imports of that country. Such decrease must have contributed importantly to a decline in sales or production. Under current law, Commerce may only provide such assistance to a firm upon a determination that increases of imports of articles or services like or directly competitive with the firm's articles or services contributed importantly to a decline in sales or production.