
Cardi B and Offset are already married, and documents show they actually tied the knot MONTHS ago -- which explains why he's now calling her his "wife" in public.
We did some digging and found out they got a marriage certificate in Fulton County, GA on Sept. 20, 2017. For you single folks ... the marriage certificate is filed with the court AFTER a couple does the deed as proof the marriage really happened.

The secret marriage puts a new perspective on their big public engagement. You'll recall, Offset got down on one knee back in October during their performance in Philly.
https://www.instagram.com/p/BaxrmmTF12mTurns out ... Offset and Cardi are a true showbiz couple 'cause that was all for show. Now, we know they were already husband and wife for a month at that point.
http://www.tmz.com/2018/06/25/cardi-b-offset-married-marriage-license-wife/