XXXXXXXXX,
If your friend is on the title, there will no issue with her deducting half of the mortgage interest and property taxes. Is your friend also on the mortgage?
Regards,
Mark D
She can still claim half of the mortgage interest. I would have her attach a statement to the return stating she is a 50% owner of property with you. She will need to give your name an SSN on the statement as well. This will help prevent any IRS document matching problems later on down the road.
Enrolled Agent
MBA, EA, Specializing in Business and Individual Tax Returns and Issues