Solmonese said federal policy runs increasingly counter to what many employers are doing. "They see this not just as an issue of workplace equity but, for a whole range of reasons, [as] something that makes a lot of sense," he said.
Forty to 45 percent of the Fortune 500 companies offer domestic partner benefits, Abbott said. Among all large employers, those with more than 1,000 workers, the figure is about 30 percent, he said.
Among all businesses, "the number drops to 15 to 20 percent because many small businesses either simply can't afford the benefit" or their owners may object for personal reasons, he said.
Early on, there was "enormous concern that including same-sex partners would create crippling costs," Abbott said. "That has proven not to be the case. Generally, what we have found is the cost of domestic partner benefits has been nominal," about the same for same-sex and a little higher for opposite-sex unmarried partners as for spouses. Domestic partner benefits can escape tax if the non-employee partner can qualify as the employee partner's dependent. Children of the non-employee partner may also qualify this way.
To qualify, the partners must, among other things, live together, and the employee partner must provide more than half the non-employee's support. Some employers provide worksheets for employees to help figure out if they qualify.
For many couples, "it's difficult to meet that definition of dependent," Colwell said.
Jessup has considered claiming Chenoweth as a dependent but hasn't tried it.
"The tax laws are confusing. We need to talk to specialists," Jessup said. "We don't understand what that would do to his tax situation. He's self-employed -- how is that going to impact his business? It's complex and somewhat overwhelming."
There have been efforts in Congress to ease the tax treatment of health insurance for domestic partners, but they have stalled. Sens. Gordon Smith (R-Ore.) and Charles E. Schumer (D-N.Y.) plan to reintroduce legislation that would bring the treatment more in line with that of married couples.
Jessup and others at J.P. Morgan say they appreciate what the firm has done for them. A company spokesman noted that J.P. Morgan has provided domestic partner benefits since 1994 and was the first Wall Street firm to do so.
But even for investment bankers, the tax hit is not negligible.
Five years ago, when Laureen Callo's partner decided to leave J.P. Morgan and go back to graduate school, Callo added her as a domestic partner.
"It's much more affordable" than other options they looked at, but it resulted in $5,000 a year in additional taxable income. "In the 35 percent tax bracket . . . you are talking about $1,800 a year in tax saving" they would have been allowed if they were married, Callo said. "Over five or six years, that's not small change."
