Your marital status is determined by your status as of December 31, 2013. If you separated in 2014 you are considered as being married in 2013. If you separated late in 2013 and were separated for 90 consecutive days ( even if the period extends into 2014) will be considered as being separated in 2013. You must live separate and apart to claim as separated. Marital status is very complicated. Filing with the incorrect marital status can cost you many unnecessary tax dollars.