There is much speculation after the oral arguments in Windsor v United States that the Defense of Marriage Act (DOMA) may fall by the end of June (the likely time that the United States Supreme Court will issue its opinion in the case). If DOMA falls in June there are some things to think about now regarding you income taxes.
First, if you are a same-sex married couple who will pay a lower tax bill if you file jointly, and if you were legally married in 2009 or before, you should consider filing an amended return before April 15 this year. That is because there is a three year statute of limitations that applies to the filing of amended tax returns, and so if you wait to see what the Supreme Court does in June, and if the Court does indeed strike down DOMA, the statute will have run for tax year 2009.
If you are a same-sex married couple who will pay a higher tax bill once you are required to file jointly, you might consider cancelling that trip to Paris and putting the money in your savings account to cover the higher tax bill you will face for 2013. Couples that include two-earners are generally likely to pay a higher tax bill when required to file jointly. And if the Windsor opinion does strike down DOMA, you should consult with your tax professional about how much to increase your withholding or your estimated tax payments so that when you file for 2013 you will not owe a penalty for underpayment of tax.