What must a property owner provide to claim mortgage interest on their tax return?

To claim mortgage interest on their tax return, a property owner is required to provide a copy of the mortgage agreement. This document serves as official proof of the loan and outlines the terms of the mortgage, including the amount borrowed and the interest rate. It is essential for accurately reporting the interest paid because the IRS needs to verify that the taxpayer is indeed the borrower who incurred the debt with the lender.

This requirement helps ensure that the claimed interest deduction is legitimate and tied to an actual mortgage obligation. While tracking payments, establishing property value appreciation, or showing property taxes may be relevant in different contexts, they do not serve the specific purpose of substantiating the mortgage interest deduction for tax purposes. The mortgage agreement is the foundational legal document that connects the borrower to the interest being claimed on their tax return.