You can check the box on line 1 if any of the following was true on December 31, 2014. You were never married. You were legally separated according to your state law under a decree of divorce or separate maintenance. But if, at the end of 2014, your divorce was not final (an interlocutory decree), you are considered married and cannot check the box on line 1. You were widowed before January 1, 2014, and did not remarry before the end of 2014. But if you have a dependent child, you may be able to use the qualifying widow(er) filing status. See the instructions for line 5.
Married Filing Jointly
You can check the box on line 2 if any of the following apply. You were married at the end of 2014, even if you did not live with your spouse at the end of 2014. Your spouse died in 2014 and you did not remarry in 2014. You were married at the end of 2014, and your spouse died in 2015 before filing a 2014 return.
Married Filing Separately
If you are married and file a separate return, you generally report only your own income, exemptions, deductions, and credits. Generally, you are responsible only for the tax on your own income. Different rules apply to people in community property states; see Pub. 555.
Head of Household
This filing status is for unmarried individuals who provide a home for certain other persons. You are considered unmarried for this purpose if any of the following applies. You were legally separated according to your state law under a decree of divorce or separate maintenance at the end of 2014. But if, at the end of 2014, your divorce was not final (an interlocutory decree), you are considered married. You are married but lived apart from your spouse for the last 6 months of 2014 and you meet the other rules under Married persons who live apart. You are married to a nonresident alien at any time during the year and you do not choose to treat him or her as a resident alien.
Qualifying Widow(er) With Dependent Child You can check the box on line 5 and use joint return tax rates for 2014 if all of the following apply.
Your spouse died in 2012 or 2013 and you did not remarry before the end of 2014.
You have a child or stepchild you can claim as a dependent on line 6c. This does not include a foster child.
This child lived in your home for all of 2014. If the child did not live with you for the required time, see Exception to time lived with you, later.
You paid over half the cost of keeping up your home.
You could have filed a joint return with your spouse the year he or she died, even if you did not actually do so.