Underwriting Taxes When Buying New Multifamily Development

I am curious how others are going about this from an acquisition standpoint.

I realize most buyers are buying existing, usually value add properties. And estimating taxes on existing, older assets is pretty straightforward compared to a new project that is not yet complete or stabilized. 

Whats the best way to go about this when 2 or 3 years ago it was simply dirt.  And now its a multimillion dollar asset.  

Whats the best way to approach this to ensure you are at least in a tolerable range when estimating the taxes for UW purposes.