I don't understand why the income would be reported. I've been trying to get an answer on this too and by research leads me to believe the income shouldn't be reported.
Publication 527 says: Used as a home but rented less than 15 days. If you use a dwelling unit as a home and you rent it less than 15 days during the year, its primary function isn’t considered to be rental and it shouldn’t be reported on Schedule E (Form 1040 or 1040-SR). You aren’t required to report the rental income and rental expenses from this activity. The expenses, including mortgage interest, property taxes, and any qualified casualty loss will be reported as normally allowed on Schedule A (Form 1040 or 1040-SR). See the Instructions for Schedule A for more information on deducting these expenses.
Since days rented at a below fair value price (below market rent) to a family member is not considered a a rental day, then if you rented to a family member for the full year at a below market rate, then none of those days would be considered rental days. Therefore I think it would qualify for the reporting exclusion above. Can you tell me why you think this income should be reported?
