Data from the 2005 American Community Survey (ACS) form the basis for most of the
estimates in this report. However, the limited historical data regarding marriage between
same-sex couples in the United States required using a number of assumptions to build on
these basic figures and construct estimates of the economic and fiscal impacts of legalized
marriage for same-sex couples. These assumptions included, for example, the likelihood that
a same-sex couple will marry or be covered by health insurance. Throughout the report, we
assume that 51 percent of same-sex couples identified through the ACS will marry if given
the opportunity, based on the experience of Massachusetts.