This Student Comment explores the long-standing gender bias inherent in the United States Internal Revenue Code (“IRC”). Specifically, this Comment discusses the bias of the taxing code against secondary earners in dual-income families. Under the IRC, primary earners in a dual-income household are taxed at a much lower rate than secondary earners in the household. As women have historically suffered from lower wages and income than their husbands, the effect of the IRC is to tax married women at much higher rates than married men. Indeed, the average working married woman loses over two-thirds of her pay to income taxes. Over the past several decades, Congress has attempted to amend the IRC to eliminate this secondary earner bias. However, such attempts have failed to bring the United States’ tax system up to par with other countries. In an effort to push for reform in the IRC, this Comment takes a comparative look at how secondary earners, particularly married women, are treated in the tax systems of the United Kingdom, Ireland, and Malaysia. Based on the lessons of these countries, this Comment proposes various amendments to the IRC to eliminate the secondary earner bias inherent in the tax system.