This legislation aims to modernize the Internal Revenue Code to ensure that all legally married couples, particularly same-sex couples, are treated equally under tax law. It seeks to eliminate gender-specific language and clarify tax rules, allowing same-sex couples to amend their tax filing status and access benefits previously unavailable to them. Key provisions include enabling legally married same-sex couples to amend their income tax returns to file jointly, even if they initially filed separately due to their legal status at the time.