WASHINGTON » In the dining room of their townhouse here, David Huebner and John Barabino were the picture of prosperous domesticity this week. A housekeeper padded about, work on their outdoor patio continued and their 3-year-old son, Miles, napped upstairs.

But together, they put a human face on an uncomfortable truth: Huebner and Barabino’s union, although legal, is still not equal to that of their heterosexual friends, even after historic Supreme Court rulings to grant federal benefits to legally married gay couples and restore same-sex marriage in California.

While the plaintiff in the Defense of Marriage Act case, Edith Windsor, will get back $363,000 in federal estate taxes — "with interest," her lawyer, Roberta Kaplan, said — the future is not so clear for Huebner and Barabino. They married in California (before the now-overturned ban) and adopted their son there. Their primary home is in Utah, which does not recognize their marriage. But they live part time in Washington, which does.

They are among thousands of legally married same-sex couples, married in one state but living in another, caught in a confusing web of laws and regulations. It is a predicament the Obama administration is only beginning to grapple with: how to extend federal rights and benefits to same-sex couples when states, not the federal government, dictate who is married.

"The couples in those states also have skim-milk marriages," said Kaplan, referring to a remark by Justice Ruth Bader Ginsburg. "It’s just the flip side, in the sense that they may have marriages that are recognized by federal law, but not state law."

Taxes are a big concern. The Internal Revenue Service will determine whether Huebner, 40, a psychology professor at the University of Utah, and Barabino, 44, a former Google executive and stay-at-home father, may file jointly and claim the marriage deduction long offered to heterosexual couples. But no matter what the agency decides, they must still file separately in Utah.

Should one die in Washington, the other would receive Social Security benefits because of the court’s decision, legal experts said. But in Utah, the surviving spouse would get nothing since federal law dictates payments based on the "state of domicile," not the "state of celebration." Only Congress can change that.

"There are two standards," Huebner said. Given their residence in two states, "for us, it’s even more complicated."

Eliminating these cross-border inequities and making same-sex marriage the law of the land is the next frontier for gay rights advocates. A day after the ruling, Chad H. Griffin, the president of the Human Rights Campaign, appeared at a gay community center in Utah – where gay couples cannot adopt and even domestic partnerships are banned – to draw a pointed distinction with California, where gay men and lesbians will be able to begin marrying again soon.

"We cannot tolerate the persistence of two Americas when it comes to equality," Griffin said.

If the prospect of "two Americas" is a problem for Griffin, it also troubles Brian S. Brown, the president of the National Organization for Marriage, a conservative advocacy group. In an interview, he vowed to "roll back gay marriage" wherever it exists, adding, "Ultimately, as Lincoln said, we can’t have a country half slave and half free."

There are an estimated 650,000 same-sex couples in the United States, and 114,000 of them are legally married, according to the Williams Institute at the University of California, Los Angeles. It will be easy for the federal government to extend more than 1,000 benefits to those living in states where they wed. For the rest, the path is murkier.

After their daughter, Soleil, was born six years ago, Mindy Stokes and Katie Rathmell left Florida for a friendlier climate in Oregon, where they registered as domestic partners. Last year, same-sex marriage became legal in neighboring Washington state. Two weeks ago, they drove across the Columbia River from their home in Astoria, crossed the border and had a wedding.

Rathmell, a research associate for an oceanography group at Oregon Health and Science University, provides the family’s health insurance but has been paying taxes on the benefit for Stokes and their daughter. The couple is hoping that will change soon. Even if it does, they still expect to pay more for other coverage, like car insurance. Without an Oregon marriage certificate, they do not get a marriage discount.

"I have rights to visit Katie in the hospital, and we can leave property to each other, I think," Stokes said. "But it’s so complicated and convoluted. It would be much easier and cheaper if it just passed nationwide."

Angela Hughey and Sheri Owens, who married in California but live in Arizona, were so eager for the court’s decision that they contacted the IRS in March and received instructions on how to file a request to amend past returns. But Hughey, whose business, One Community, caters to gay professionals, said that taxes were hardly her chief concern. Arizona is one of 29 states that still allow discrimination based on sexual orientation.

"You’re talking about a community that is treated with great disrespect and disregard," she said.

Advocates are hoping that Wednesday’s rulings will create new momentum for other gay rights advances, like passing a federal law barring employment discrimination. As for marriage, their goal is to build "a critical mass of states and a critical mass of public support that together create a climate for the Supreme Court to finish the job," said Evan Wolfson, founder of Freedom to Marry, an advocacy group.

In the meantime, the byzantine maze of laws has created a boon for lawyers who advise same-sex couples on matters like adoption and estate planning. Among them is Laura Milliken Gray, of Salt Lake City, who said she goes through "all kinds of gyrations" for couples who "want to achieve family equality that their straight brothers and sisters have."

Gray advised one client, Craig Crawford, who sells computer networks in Salt Lake City, that he would have to write all possible heirs — his parents, siblings and their children — out of his will to ensure that his property could be left to his husband, who is technically not next of kin under Utah law. Crawford was stunned.

"When you have to write your mother’s name down and disown her," he said, "that is really harsh."

Same-sex couples have long made decisions about where to live, work and raise children based on the legal climate. That is true of Huebner and Barabino, who met in San Francisco when Huebner was teaching there and Barabino was working for Google.

Through two moves — one to Washington, where Huebner taught briefly at the University of Maryland, and then to Salt Lake City — they kept their home in San Francisco. Once living in Utah, their California residency became important, Huebner said, because they needed access to the California courts to adopt a child.

When they moved to Utah, Huebner said, "it wasn’t important that the state doesn’t recognize our marriage," because neither did the federal government. But with the court decision, he is beginning to wonder.

"If by choosing to live in Utah we are choosing not to have federal rights," he said, "it changes my decision matrix."

When the rulings came down Wednesday, the couple took Miles to the Supreme Court to watch history being made. There, they met up with friends who have a baby and a 3-year-old. While the toddlers romped on a lawn across the street from the court, the parents checked their cellphones for news. A cheer went up from the crowd when the Defense of Marriage decision was announced.

"We’re married!" Barabino said, cradling Miles in his arms. "It’s crazy. Because of the soil that we’re standing on now, because we stand in D.C., we’re married. When we stand in Utah, we are not."

© 2013 The New York Times Company