Tax filing status in the US is often contradictory, and definitely less than intuitive. If you get married, the IRS treats you as married all year – great for tax savings. But it’s also true of divorce; divorced on December 31 is divorced all year – which is lost tax savings. Married to a US nonresident? If your spouse doesn’t have a US tax number, it can keep you from filing your returns electronically. But if you have a dependent, you are considered unmarried and can file head of household. Domestic partners and common law marriages don’t count as married, but any valid marriage in a foreign country does. Our recommendation: Avoid assumptions about how you are going to file, and file truthfully.