Multi-family rental (unit 1: 1bed 1bath. Unit 2: 2bed 1 bath). In 2023, one unit was remodeled and rented. The other unit also fire damaged will not be ready until 2024.

You can prorate the cost basis and property taxes between the two units since one unit is being rented and needs to be reported for your 2023 tax return. 

Prorate the costs based on the square feet of each unit relative to the total square feet of both.  If they are equal in size, then divide the cost basis and property taxes in half and enter information in your return for only the unit that has been rented so far.  You can enter the same address for both properties, just add a descriptor showing that there are two different properties being considered as rentals (unit 1, unit 2 for example).  Keep some notes for yourself to explain how you decide to prorate the expenses.