How to deduct proper mortgage interest for Airbnb Room in a house

Hi

 

I rented a bedroom of my home using Airbnb. I am planning to use Schedule E, but TurboTax does not ask me about how big is the area/room for this rental.

 

To deduct the home mortgage interest, it uses the total of days rented and the personal day use. So, should I put only the mortgage interest percentage of the area used for Airbnb and then TurboTax calculates the split between rented/personal use?