]I ran some numbers through a federal income tax calculator to provide an example of income tax advantage for you. Assume we have two people, one who earns $50,000 per year and one who earns $30,000 per year. Filing as single people, the total tax due is $6,093 + $2,603 = $8,696. If our couple files jointly as a married couple, their tax bill on the same incomes is $8,205.
Conclusion: if you're in a relationship with a same sex partner at these income levels and unable to get married, the government is legally entitled to take an extra $500 from you versus a similarly situated straight couple that can get married.