@thejendavis2014 To deduct home mortgage interest, you must have a legal and/or equitable ownership interest in the home. Legal ownership is documented in the deed to the home. You stated that you and your fiance are co-owners of the home but only you are liable on the mortgage. If so, your fiance should be named on the deed of trust establishing a legal ownership interest.
If your fiance is not a legal co-owner but living in the home with an equitable ownership interest, they can still deduct the interest they paid even if they are not named on the deed and are not liable on the mortgage. With equitable ownership, they enjoy the benefits and burdens of ownership. However, this can be a difficult way to go. Your fiance must be prepared to show they enjoyed the benefits of ownership as well as a fair share of the burdens of ownership.
Whether your fiance claims legal or equitable ownership interest, they will have to file a paper return and attach a statement explaining which party received the 1098 and how much interest each of you paid (See More Than One Borrower at the bottom of page 8 of Pub 936).
