This year's tax day marks a historic event for one group of Americans: April 18 will be the first time that every married same-sex couple in the country can file both their federal and state taxes together.

It's something Colleen and Linda Squires have been waiting for for a long time.

They met in Boston in November 1986 and held a commitment ceremony in 1992. They waited until 2004 — 12 years — before Massachusetts became the first state to legalize same-sex marriage.

"We totally picked the right state to be in," Linda says. "You know, it's not something I ever thought I would see in my lifetime."

That meant that they could file their Massachusetts state taxes, but not their federal taxes, as a married couple.

Fast forward to 2012. The Squires moved to Michigan, where Colleen was called to serve as a pastor for a Unitarian church in Grand Rapids. Michigan did not recognize their Massachusetts marriage.

"I was the person in the room that could actually perform weddings," Colleen recalls. "But my marriage to Linda was not seen as a legal marriage in the state we lived in now."

As a result, Colleen and Linda were back to filing state and federal taxes as if they were single.

But their status changed again in 2013, when the Supreme Court struck down the federal portions of the Defense of Marriage Act. That allowed same-sex couples to file federal taxes as would any married couple.

But they still couldn't file their Michigan state taxes together — until the Supreme Court legalized same-sex marriage across the land last year.

So this tax day is the first time in nearly 30 years together they can actually file as a married couple for both federal and state taxes.

It meant a lot, Colleen says. "It's acknowledgement or treating us equally," she says. "We've been together for so long. It was feeling like we were respected."

There are thousands of married same-sex couples for whom this tax year is a major step toward simplicity — before 2015, filing taxes was a real nightmare.

For example, if a couple lived in a state that did not recognize their marriage, a same-sex couple would have to file one federal return as married and two separate state returns as if they were single.

And because some state returns were based on the information given to the feds, a same-sex couple also would have to draw up two mock federal returns as if they were single.

"The entire process was so frustrating and nonsensical," says Robin Maril, a tax policy expert and senior legislative counsel for the Human Rights Campaign, which is based in Washington, D.C. Maril's wife teaches tax law and does their taxes.

"I would definitely come home from work and she would be almost in tears," Maril says.

Now same-sex couples face some of the same decisions as heterosexual couples. For instance, what happens when filing jointly pushes you into a higher tax bracket?

That happened to David Lantrip and his husband in Houston.

"That was a little bit of a surprise to both of us," Lantrip says about discovering that filing jointly as a married couple meant paying higher taxes. They weren't happy about it.

But Lantrip says it's small price for the legal protections of marriage.

"The peace of mind and the satisfaction is really what was important," he says.

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