Duplex - to zero-lot-line or not (subdivide)

[Marcel Crudele]

I'm working on being very clever and realized I might be trying to be too clever... I could use some advice.

OVERVIEW

I have a sfh + ADU in a very popular part of Atlanta - Old Fourth Ward. I'm using the ADU as a STR and it is doing great!

My plan (currently at permitting) has been to replace the sfh with a Duplex with the ADU assigned to Unit A and Unit B its own property - subdivided with a zero-lot-line. I would live in Unit A and rent out the others, but a backup, emergency plan would be to sell Unit B if needed.

Financing would come from a construction loan and, after construction, I would "buy" Unit A and the ADU from myself with a personal mortgage and let the interest-only construction loan convert into a 20-year loan on whatever the balance is for Unit B - the expectation being that personal mortgage terms would be better than converted construction loan terms.

I could always refinance Unit B later if it made sense. This plan has been discussed with the bank.

THE QUESTION

Should I split the properties as described or keep it as a single duplex property? While dividing the lot gives me the flexibility to easily sell one of the units, keeping them together would allow me to refi the entire property at a lower rate and potentially reduce the total property tax (I'm making that last part up, but it seems like it could be the case).

Any help would be appreciated.