You must:

Only claim your own share of the real estate tax payments, including water and sewer use charges, that are related to the part of the residence you use and occupy as your principal residence. For example, if a condominium association pays the sewer and water bill for multiple owners, each owner may only claim their own proportional share of the charges paid that are related to their own condominium.

Assess the properties that are related to the part of the residence you use and occupy as your principal residence. For example, if you own more than 1 acre of land, use only the assessed value of your principal residence (together with the immediate surrounding land that's associated with that residence) that's smaller than 1 acre when determining if you're eligible for the credit.