Same-sex marriages were recognized by the federal government in 2013 when the Supreme Court invalidated a key provision of the 1996 Defense of Marriage Act (Windsor v. United States) and allowed same-sex couples to be treated as married for all federal tax purposes, as long as they were legally married in a state that recognized their marriage. In 2015, the court went further, establishing via their decision in Obergefell v. Hodges that same-sex couples have the right to marry in all states.

In “Same-sex married tax filers after Windsor and Obergefell” (PDF), Brookings Senior Fellow Adam Looney, along with Robin Fisher and Geof Gee at the Treasury Department Office of Tax Analysis, examine data from jointly-filed tax returns to provide the first analysis of marriage patterns of same-sex couples in the years immediately following the significant Supreme Court rulings.

When compared with different-sex couples filing jointly, the analysis reveals that same-sex joint filers are generally younger, higher income, and less likely to claim dependent children.

How many same-sex married couples filed taxes?

The authors estimate that about 250,450 same-sex couples filed joint tax returns in 2015. Over the prior two years, the number of same-sex filers increased by about 40 percent each year, from about 131,080 filers in 2013 and 183,280 in 2014.

Figure 1 compares the number of same-sex filers by state of residence in 2013—the year of the Windsor decision—with those filing jointly in 2015 when same-sex marriage was recognized nationwide. The states are grouped according to the year same-sex marriages was legalized in that state—either by a state-specific action in 2013 or 2014, or by default after the Obergefell decision in 2015. The blue bars in states where same-sex marriage was not legal until 2014 or 2015 represent joint filers that were married in a state other than their state of residence (that is: they got married in a state where same-sex marriage was legal in 2013, but lived permanently in another state).

In general, overall rates of same-sex filing in 2015 were highest in states that had legalized same-sex marriage prior to 2013 or in 2013. In states that had not legalized same-sex marriage until 2015, rates were relatively lower up to and including the year 2015. The percentage increase in same-sex filing, however, was relatively high in those states.

Demographics of same-sex married couples

When compared with different-sex couples filing jointly, the analysis reveals that same-sex joint filers are generally younger, higher income, and less likely to claim dependent children. In 2015, 48 percent of different-sex couples claimed children as dependents, compared with 28 percent of female-female couples and just 7 percent of male-male couples. Same sex joint filers are also more likely to live in metropolitan areas and coastal states than different-sex filers.

The analysis examines where same sex couples live in several different ways: By using geographic areas defined by state, by regional labor markets (“commuting zones”), and in select large 5-digit zip codes. Unsurprisingly, there are large differences in the number and share of same-sex couples filing in different states, with the highest proportion of same-sex filers living in coastal states, in certain metropolitan areas, and in states that had legalized same-sex marriage prior to 2013.

For the U.S. as a whole, same-sex filers made up only 0.48 percent of all joint filers in 2015, though the rates varied widely across the country. In Washington D.C., for instance, which had some of the highest shares of male-male filers, same-sex couples accounted for approximately 4.2 percent of all married filers. States in the south and Midwest had the smallest shares of same-sex filers. In Mississippi and North Dakota, they made up just 0.2 percent of all filers.

Same-sex filers in the 100 largest commuting zones, 2015

Order by share of marriages Commuting Zone Number Share of Marriages 1 San Francisco, CA 13,220 1.52% 2 Santa Rosa, CA 1,416 1.25% 3 Seattle, WA 9,281 1.09% 4 Boston, MA 9,458 1.04% 5 Portland, OR 4,006 0.97% 6 Miami, FL 5,131 0.92% 7 Albuquerque, NM 1,248 0.90% 8 San Diego, CA 4,845 0.88% 9 New York, NY 13,892 0.84% 10 Portland, ME 1,111 0.83%

Order by share of marriages Commuting Zone Number Share of Marriages 91 Oshkosh, WI 260 0.23% 92 Grand Rapids, MI 609 0.23% 93 Gary, IN 289 0.23% 94 Baton Rouge, LA 279 0.23% 95 Huntsville, AL 256 0.22% 96 Greenville, SC 374 0.21% 97 Johnson City, TN 228 0.21% 98 Youngstown, OH 194 0.15% 99 Brownsville, TX 209 0.14% 100 Provo, UT 151 0.13%

But what about where same-sex filers living within those cities? See a list of the top 10 neighborhoods driving up the rate in San Francisco, New York, and more.

Related Content Brookings Now The top 10 neighborhoods where same-sex couples live after saying “I do”

Wage gaps between male-male couples and female-female couples

In addition to geographic differences, the report also sheds light on pay disparities between same-sex couples and their different-sex peers—and how the disparities differ depending on whether a couple is comprised of two men or two women.

To start with, the gap in average annual incomes of male-male couples and female-female couples is significant. When comparing the incomes of all joint-filers nationwide aged 25-55 in 2015, female-female couples earn about 68 percent of what male-male couples earn. That’s roughly 10 percentage points greater than the widely cited “wage gap”—that women earn on average $0.78 for every $1 men earn.

What about the gap between same-sex couples and their different-sex peers? For 2015 filers nationwide between the ages of 25 and 55, average household incomes for male same-sex couples was higher than household incomes of different-sex couples. Male-male couples earned about $168,233 and different-sex couples earned about $119,803. That’s a gain of about $48,000 for male-male couples. Meanwhile female-female couples made less than their different-sex peers—about $5,000 less. Female-female joint filers earned about $115,094.

But much of this can be explained by the concentration of same-sex couples in higher-income coastal states and metropolitan areas. When adjusting to account for location, the gap between the incomes of same-sex and different-sex couples shrinks for men, but grows for women. When comparing same-sex couples with different-sex couples in their own neighborhoods, the analysis reveals that while male-male couples still earn, on average, about $15,000 (or 10 percent) more than different-sex couples, female-female couples actually earn about $16,000 (12 percent) less than their different-sex neighbors.

When adjusting to account for location, the gap between the incomes of same-sex and different-sex couples shrinks for men, but grows for women.

In other words, some of the gap is related to where these couples live, specifically, and that male-male couples are more likely to live in places like San Francisco or New York, where the average resident earns a higher income than other areas nationwide.

“This wage gap between male and female same-sex couples partially reflects factors that are obvious in the data, like the concentration of male couples in higher-cost areas, and the much larger share of female couples with child care responsibilities,” Looney says. “But those factors—or others, like education or occupation—are unlikely to explain all of the remaining wage gap, which most economists attribute to a combination of labor market discrimination and a wage penalty for taking time out of the labor market for child-rearing or for part-time work.”

Gaps in average household annual income, 2015 filers

Same-sex couples and different-sex couples aged 25-55

Male-male Average Income (nationwide) Average Income, Adjusted by Geography Male-male couples $168,233 $168,233 Different-sex couples $119,803 $152,608 Gap with same-sex couples +$48,430 +$15,625

Female-female Average Income (nationwide) Average Income, Adjusted by Geography Female-female couples $115,094 $115,094 Different-sex couples $119,803 $131,116 Gap with same-sex couples -$4,709 -$16,022

Conclusion

The Supreme Court rulings culminated a period of rapid changes in the legal recognition and rights of same-sex couples. Statisticians, demographers, and social scientists are still trying to catch up. It was not until 2014 that the Census Bureau statistics counted same-sex married couples as co-habituating partners. Indeed, in previous decades, Census assumed that couples who reported being in same-sex relationships had checked the wrong box on the Decennial Census and other Census surveys. Further complicating the matter, many sample-based estimates not only lack statistical power to measure with precision the number or characteristics of smaller populations, such as the population of same-sex couples or gay and lesbian individuals, but also include measurement errors that poses particular challenges in identifying same-sex couples amidst the much larger population of different-sex couples.

In this context, the analysis of IRS data is an important new contribution to understanding the demographics and economic characteristics of same-sex married couples in the U.S. during a period of political importance and major shifts in civil rights.

Download the full paper here (PDF).

The authors did not receive financial support from any firm or person for this article or from any firm or person with a financial or political interest in this article. They are currently not an officer, director, or board member of any organization with an interest in this article.