IF disabled dependent adult son live in an apt. I own for zero rent. can the expenses be considered as loss to be deducted from other income in filing my taxes?

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

• They're related to you.
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They're under the age of 19 (or 24 for full-time students).
• No age limit for permanently and totally disabled children.
• They lived with you for more than half the year (exceptions apply).
• They didn't provide more than half of their own support for the year.

Qualifying relative

• They don't have to be related to you (despite the name).
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They lived with you the entire year (exceptions apply).
• They made less than $4,400 in 2022.
• You provided more than half of their financial support.

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.