My son has paid for my house for the last three years. How can he claim the mortgage interest?

[DianeW777]

It depends. If he does not own the house and his name is not on the deed he cannot claim the mortgage interest.  

• IRS Publication 936

If he is part owner of the home, and is responsible for the mortgage loan, and this is his main home he can deduct the interest on itemized deductions.

[texbuddywright1]

Even if he is buying through me like rent to own and we have a contract

[DianeW777]

Rent is not the same as a sale, however you said you have an installment agreement in place. If you have sold your home to your son, and you do have a contract for installment it's possible he can deduct the mortgage interest as his main home or his second home.  This assumes you have reported the sale of your home on your tax return.  

You should have or can have created for you the amortization schedule showing the interest paid to you by your son, even it it goes directly to the mortgage lender. He would enter the interest as a seller financed amount.

• Go to Deductions and Credits > Scroll to Mortgage Interest > Continue to 'Enter it myself' > Select 'The seller is financing this loan .....
• Continue to enter the mortgage interest.

You would report the interest income on your tax return.  Seller financed interest goes in the same place as the bank interest.