Since your son has an ownership interest in the house (he is on the deed), he can deduct the mortgage interest and property taxes that he paid, subject to IRS limitations on the amount.
Since you did not pay any of the mortgage interest or property tax, there is nothing for you to deduct on your own return.
A gift tax return (IRS Form 709) must be filed on any gift over $15,000 (2018) made to any one person in any one year. If you add someone's name to the deed on your property, the IRS may view it as a gift of one-half the value of the property. The current (2018) federal estate and gift tax lifetime limit is $11,180,000 - so it is extremely unlikely that you'll have to actually pay any gift tax. The reason for Form 709 is for the IRS to keep track of your gifts, which count against that lifetime limit.
https://www.irs.gov/pub/irs-pdf/f709.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
