Tax Deduction Question for New Windows

[Andrew P.]

I recently decided to replace many of my windows in one of my multi-unit properties and I went with the contractor's loan company (AquaFinance) to pay for the windows. All in all, I spent 12k on the windows with a 9% interest and by the end of this year, I will probably have paid almost $600 this year in principal and interest. Am I eligble to write off the windows and if so, in what manner? Do I write off the original cost of the windows or do I write off how much I paid the loan company so far. If it is this route, can I write off the principal and the interest? Also, is it normal to expect some sort of tax form from the loan company at the end of the year? Thank you everyone for your help.