If I purchased a rental property in 2025 as 50% owner, do i put the entire original purchase price, or half of it (in the section to determine cost basis and depreciation

[pk]

@flores-jamie2015 , if you are not filing jointly with the other 50% owner, then it is best  to declare the proeprty as 100% ownership on your  fifty percent  i.e.  it is as if you bought a  rental property for 50% of the cost including 50% of the improved structure and 50% of land underneath.  You then also have  rent  and costs  all allocated to you as 50% of the total for the property  ( but at 100% of your fifty percent -- as if  you had a rental property with two condos in the same building, you own one and your partner owns the other condo ).  

Does his make sense ?  Or am I confusing you  more than I should ?

Is there more I can do for you ?

[DavidD66]

You use 50% of all values for your reporting of the rental property:  cost basis when setting up the asset, rent, expenses, etc.   Make sure you allocate a portion of your cost basis to a separate land asset when setting  up.

[Mike9241]

there is also the question of how the other owner is related to the taxpayer and wether this is an LLC . Technically a partnership return might be required.