You may get breaks—and penalties, too. By Sandra Block, Senior Editor From Kiplinger's Personal Finance, December 2013 Legally married same-sex couples are now considered married for federal tax purposes. Tax bills could drop for couples if one spouse earns a lot more than the other. But dual-income couples who earn about the same amount will likely end up paying a marriage penalty, just like any married couple. If both partners earn $100,000, filing jointly results in a penalty of $879, according to the Congressional Research Service. But if one partner earns $50,000 and the other $150,000, filing jointly shaves their bill by $557.See Also: Kiplinger's State-by-State Guide to Taxes If you suspect you’re headed for a penalty, look for ways to cut your tax bill, such as boosting charitable contributions before year-end (see 4 Smart Year-End Moves to Trim Your 2013 Tax Bill). If you’re getting married next year and will be in a higher tax bracket, consider deferring deductible expenses until after January 1. As your tax bracket increases, those deductions will be more valuable. Planning a December wedding? If being married will result in higher taxes, consider delaying the nuptials until the new year. If you get hitched by December 31, Uncle Sam considers you married for the entire year. Anyone legally married in 2010, 2011 or 2012 should run the numbers to see whether amending two single-filer tax returns to a joint return will save you money. (You aren't required to amend previously filed returns.) You have until April 15, 2014, to amend a 2010 return.