Mortgages are limited to 2 residences, but you can deduct unlimited Real Estate taxes.
If "investment property" means rental property, those taxes go on Schedule E.
If it is just vacant land held for investment, I think you need to file an election to add the taxes to Basis.
<a rel="nofollow" target="_blank" href="
https://www.law.cornell.edu/cfr/text/26/1.266-1">https://www.law.cornell.edu/cfr/text/26/1.266-1</a>
