Dear Stata specialist,

I need help with survival analysis, here is the story. I am currently working on a project to use survival analysis to study the retention rate of new immigrants in rural areas.
The time variable is the year (year 1, year 2, year 3..... etc), and the event is retention (0 if immigrants stay in a rural area in the year, 1 if immigrants leave a rural area in the year). The failure is event=1
My question is I am trying to use marital status (it is a categorical variable that has 3 groups: married/common-law; single; separated/widowed/divorced) as one factor in my cox regression, however, one challenge is that it may be possible maybe some immigrants in year 1 is single, in year 2 is still single, but then in year 3, his status changed to married.

In this case, how should I code the variable for marital status? Is there a way to do it?? Please advise.

Thanks
Yuchen