My son has zero income, he is mentally disabled, and refuse to ask for social security income or benefits.
So sorry for your difficult situation. You are not receiving any rent for the apartment so you cannot deduct the usual expenses that you could use if you had a renter paying market value rent. If you own the property you can enter the mortgage interest and property tax you paid -- like a second home. But that's it. And if you are supporting your son, he can be claimed as a dependent on your tax return if he meets the criteria to be claimed.
WHO CAN I CLAIM AS A DEPENDENT?
You can claim a child, relative, friend, or fiancé (etc.) as a dependent on your 2022 taxes as long as they meet the following requirements:
Qualifying child
Qualifying relative
When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them. There may be other tax benefits you can get when you claim a dependent.
You may be able to deduct the mortgage interest and property taxes you pay for the apartment, but you cannot deduct any of the other expenses. If your son were to receive Social Security Disability, you could charge rent, and deduct your expenses up to the amount of the rent you receive.