Marital Status

• The Internal Revenue Service recognizes five tax filing statuses: single, married filing jointly, married filing separate returns, head of household, and qualifying widow or widower. The IRS considers the taxpayer's marital status as of the last day of the year to be her marital status for the entire year. The IRS also defaults to the laws of the state where the married couple resides to determine whether or not they are legally married. A married couple who are separated but not legally divorced as of the last day of the year are still considered married for income tax purposes by the IRS.
  
  

Joint or Separate Returns

• A married couple who are separated but not legally divorced has the option of filing their taxes jointly or separately. The married filing jointly status usually results in a lower overall tax obligation, according to the IRS. The couple may elect to file separate returns, which allows each spouse to be responsible only for paying his or her own taxes. In some cases, filing separate returns provides a lower individual tax obligation. If one spouse files a separate return, both spouses must file separate returns.
  
  

Head of Household

• A married taxpayer who is separated but not legally divorced may be able to file her taxes as head of household if she meets certain requirements. The taxpayer must have paid more than 50 percent of the cost of maintaining a household for the entire tax year. The taxpayer's spouse can't have lived in the home during the final six months of the tax year. A qualifying person, such as a dependent child, must have lived in the home with the taxpayer for at least half of the tax year. The IRS considers taxpayers who meet these qualifications to be unmarried for tax purposes.
  
  

Legally Divorced

• The IRS considers couples to be married for tax purposes until they are legally divorced according to the laws of the state in which they reside. Taxpayers who are legally married as of the last day of the tax year may file their taxes as either married filing jointly or married filing separately. If the couple receives a final divorce decree on the last day of the year, the IRS considers them to have been divorced for the entire year. They may file their taxes as single or in some cases as head of household, but they may not file as married, either jointly or separately.