This is a tax question for the situation where the main house is 100% occupied by the owner and the carriage house/ADU is 100% dedicated for Airbnb renting (never used personally).

What about turning a particularly large garage into a unit like some people do with their "carriage house"?

thank you the next one in Charleston I will post is our first venture into the historic district were the rules and regs are quite stiff and the homes are museum grade.. you know horse drawn carriages gas light lamps very cool..

I personally don't think that anyone has any business wholesaling to house flippers, unless they have learned how to profitably flip houses themselves.Not trying to be offensive by any means, but I think most house flippers can agree that most wholesalers put the horse before the carriage. 

We are analyzing a purchase near Vista and our partner on this effort looked up the following:1. https://www.airbnb.com/rooms/14292365: Small studio rental in same area; historic converted carriage / barn = $100/night with 14 nights booked so far in May = $1400 for month2. https://www.airbnb.com/rooms/9351161: 2bd/1ba guesthouse same area; non-historic and bland = ~$95/night with 24 nights booked so far in May = $2280 for month3. https://www.airbnb.com/rooms/17674810: 1bd/1ba same area; non-historic but well designed = ~$90/night with 19 nights booked so far in June = $1710 for monthYou probably would want to do more similar analysis on Vista before proceeding with the STR route. 

I am in almost the same set up as you, a flat 2/1's, and a carriage house that I reside in. 

In FL, my wife and I turned our individual houses into rentals when we bought a house together that also had a carriage house so we had 3 rentals.

And actually my wife, @Erin Spradlin, and I are closing tomorrow on a SFH w/ a carriage house just east of downtown Colorado Springs, and we plan on Airbnb-ing both units.

The two houses are not touching or anything, and it's pretty common in the area to have carriage house apartments, so addresses that aren't actually on the street is also common (the second house does have its own house number, it isn't a 1/2 or anything.)Can anyone think of any reasons that the current owners might NOT have wanted or been able to split this property in two and sell the houses individually?

The house does have curb appeal, with a newly painted front door, new mailbox, new carriage lamp, and when I'm there, 2 petunias on the porch :DThanks everyone!