Of course, since the federal government does not recognize same-sex unions, that equal recognition still does not apply for federal tax purposes. So couples will need to maintain a double identity of sorts: one for the state, another for the federal government.

So how will couples' tax lives change? And what do they need to do differently? The state tax department recently issued guidance for these couples, outlining some of their rights and responsibilities. The changes went into effect on July 24 as part of the broader marriage equality law.