What should I put as Marital Status for 2016, if I separated from my husband but living as common-law spouse. I was officially divorced in Sept. 2016.

what was your status as of Dec 31, 2016?

I was divorced, but living with someone else as common-law spouse

When did you and your common-law spouse move in together, and were/are there any children residing with you?

If you and your common-law spouse were living together for 12 months as of Dec 31, 2016, OR the three of you were living together with a child/children as of Dec 31, 2016, then you will file as common-law.