The purpose of this legislation, known as the American Mariner Tax Fairness Act, is to change how income earned by United States merchant mariners is taxed. Specifically, it aims to classify this income as foreign earned income, which can provide tax benefits to these workers. The key provisions of the Act include a new definition of who qualifies as a United States merchant mariner and what constitutes a qualifying vessel. A merchant mariner is defined as a U.S. citizen or resident who is actively employed on a qualifying vessel for at least 90 days within a 12-month period.