Clarifying Duplex LTR/STR and tax issues

[Neil Fernandes]

I own a duplex, where one unit is being rented out as a long-term rental (LTR) and the other as a short-term rental (STR). My CPA advised me to split the generic costs such as property tax and water bills equally between both units, which seems reasonable. Additionally, while reporting these units, I should mention them as individual units, i.e., 123 Main St Upper [STR] and 123 Main St Lower [LTR].

My question is regarding the depreciation of the STR unit. Should it be depreciated over 27.5 years or 39 years? I initially thought it was 39 years, but my CPA believes it is 27.5 years. I do not want to argue with him, but I am not entirely sure about this and hence I am looking for advice.