It is sometimes a very difficult process to determine exactly how you should file your taxes.  While the option of filing as single may seem very appealing to those who are filing for divorce, there are specific guidelines that determine what your filing status should be when filing your taxes. 

First, you should understand the difference between married and unmarried.  If you are filing as unmarried, you are not able to file a joint return.  If you are filing as married, you can file a joint return, or a separate return.  The decision over which to choose if you are married, joint, or separate return is up to you and your spouse depending upon your individual preferences.

In order to claim that you are unmarried on your tax return you must have been either unmarried for the whole tax year, or meet one of the following guidelines. 

 You have been declared legally divorced by a divorce decree or by separate maintenance before the last day of the tax year, which is December 31st.  However, there is an exception to this rule, if you divorced for the sole purpose of filing as single, with the intention of remarrying the very next year you and your spouse must file as married.  There is no exception to this.  This is designed to keep parties from attempting to commit fraud when filing taxes. 

 The only other way to file as single is if you have just obtained an annulment before the end of the tax year.  Remember, an annulment says that a marriage never legally existed.  If your marriage that was annulled covers more than 1 year, you must also file an amended tax return for all years effected by the annulment that is not already closed due to the statute of limitations.  This means that you must file for the previous 3 years if that is how long you filed as married on your taxes.  It is important to change your filing status when you file the amended returns.  If you previously filed as married, you must change it to either single or head of household if you meet the requirements for head of household. 

However, as there are guidelines that cover filing as married as well.  You can file as married if you have been married for the whole year, or you are married on the last day of the tax year, which is December 31st for tax purposes.  If you have filed for divorce, but have not obtained a divorce decree by the last day of the year, you must file as married.  You cannot file as single if you have filed for divorce, the only way you are allowed to file as single is if you have obtained a divorce, and have the divorce decree signed by the last day of the tax year. 

It is advised that if you are married, you computer your taxes as filing joint and as filing separate to see how the tax is lower.  This will allow you to save as much money as possible, while still filing the correct legal status.  However, in order to file a joint return, at least one spouse must be a United States citizen or legal resident alien during the tax year.  If neither spouse is a legal resident alien, or a US citizen then a separate return must be filed in order to properly account all income that has been earned all around the world.  Regardless of the tax laws of another country, all income earned regardless of where it was earned must be claimed for US tax purposes.