I am filing for divorce, have not lived with mt soon to be ex spouse since 2015. why cant i be considered single?

[joezepped]

the system allowed me to file single last year

[SeanE1]

The IRS considers a married person married until their divorce is finalized.  They use December 31 of the tax year as the determinant.  If you were single all year until December 31, at 11 pm and was married at 11 pm, they would consider you married for the entire year.  The same thing goes for divorce.  If instead you were divorced at 11:45 pm on December 31, they would consider you divorced for the entire year. So unfortunately, if you are not divorced as of December 31, 2016, you only have the option of filing married filing separate or, if you have a child, you may file as head-of-household.

With that said, you can file any way you want to file, but I am just telling you what the tax law is.