June 26 marks the third anniversary of nationwide, legal same-sex marriage. The estimated 4 percent of the U.S. population that is lesbian, gay, or bisexual (LGB) can now benefit from the same legal status as married heterosexuals with all that entails: the right to be by a spouse’s hospital bedside, the ability to get a divorce if a relationship goes south, and potential eligibility for Social Security spousal benefits. A recent MRRC working paper by RAND researchers Italo Lopez and Michael Pollard makes a first-pass examination of marriage-rights expansion’s impact on Social Security.

Under current provisions, a couple’s secondary (lower) earner can receive Social Security spousal benefits equal to 50 percent of the primary earner’s higher benefit. Spouses who are eligible for larger benefits based on their own earnings history typically collect their own rather than the spousal benefit. To understand the potential impact of same-sex marriage, Lopez and Pollard needed estimates of the current and future LGB population and an understanding of same-sex couples’ earnings histories.

Lopez and Pollard use standard demographic techniques on data from 2015 U.S. Census Bureau’s American Community Survey (ACS), The National Longitudinal Study of Adolescent to Adult Health, the Health and Retirement Study, and the RAND American Life Panel to estimate LGB population projections. The authors estimate that in 2017 there were 308,000 to 524,000 gay men and 250,000 to 503,000 lesbian women of retirement age (66 and older). By 2040, they estimate these populations to be 465,000 to 868,000 and 364,000 to 825,000, respectively. Up to half of these populations intend to marry, according to new data collected by the Lopez and Pollard.

The researchers determined the earnings histories of same-sex couples by analyzing data from the ACS for the years 2011 to 2015. Lopez and Pollard found that the average heterosexual, married couple had $95,548 in earnings during this period, while same-sex, married male couples earned $131,519, and same-sex, married female couples earned $99,977. Earnings gaps, which would qualify secondary earners for spousal benefits, were not as common in same-sex marriages, largely due to a stronger division of labor in heterosexual households—both partners were more likely to be working in same-sex households than in heterosexual ones.

Lopez and Pollard emphasize that their estimates for spousal benefits do vary, but overall are similar for heterosexual and same-sex couples. Based on the researchers’ calculations, married male couples may be eligible to claim roughly about $8,400/year while married female couples could claim similar amounts as heterosexual couples, about $7,200.

These are early estimates, of course. The actual impact on Social Security will be determined by how many same-sex marriages there are, whether they last the 10 years required for a divorced spouse to qualify for spousal benefits, and the earnings and labor market participation of same-sex couple members.

Read the working paper here or the research brief here.