NEW YORK ( MainStreet) -- Clients often come to me confused about how they should file their tax return. Are they Single, Married or Head of Household? Your filing status is determined by your legal status on the last day of the year -- Dec. 31. If you got married on Christmas Eve you are considered by the IRS to be married for the entire year, and subject to the rules and rates for married filers. If your divorce was final Nov. 5, you are considered by the IRS to be "unmarried" for the entire year, and will file as either Single or, if you qualify, Head of Household. If a spouse is alive for at least one day of the year the IRS will treat you as being married for the entire year. If your husband passed away Jan. 17, 2012, you will still be able to file a joint return for 2012 and claim a full exemption for your deceased spouse. Over the years clients have insisted they were a Head of Household when they were in fact Single. To qualify as Head of Household, and take advantage of the better tax rate schedule, you must be unmarried Dec. 31 (or considered unmarried) and pay more than half the cost of maintaining your home, which was also the principal residence for more than half the year of a "qualifying child" or a "qualifying relative." Of course you must be a U.S. citizen or resident for the entire year. You cannot claim Head of Household status if your "qualifying relative" is not an actual relative, but just someone who lived in your home for the entire year. Generally you must claim someone as a dependent to be a Head of Household. But in the case of divorced parents where the custodial parent allows the ex-spouse to claim the child as a dependent, the custodial parent may still file as Head of Household. You can file as a "Qualified Widow(er)" for 2012 and get the benefit of the married tax rates if you are unmarried Dec. 31, your spouse passed away in 2010 or 2011, you were able to file a joint return for the deceased spouse's year of death and you paid more than half the cost of maintaining your home, which was the principal residence for the entire year of your dependent child or stepchild.